<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
	"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [

<!ENTITY RCL "<application>Recoll</application>">
<!ENTITY RCLAPPS "<ulink url='http://www.recoll.org/features.html'>http://www.recoll.org/features.html</ulink>">
<!ENTITY RCLVERSION "1.21">
<!ENTITY XAP "<application>Xapian</application>">
<!ENTITY WIKI "http://bitbucket.org/medoc/recoll/wiki/">
]>

<book lang="en">
  
  <bookinfo>
    <title>Recoll user manual</title>

    <author>
      <firstname>Jean-Francois</firstname>
      <surname>Dockes</surname>
      <affiliation>
        <address><email>jfd@recoll.org</email></address>
      </affiliation>
    </author>

    <copyright>
      <year>2005-2015</year>
      <holder role="mailto:jfd@recoll.org">Jean-Francois Dockes</holder>
    </copyright>
    <abstract>

    <para><literal>Permission is granted to copy, distribute and/or
    modify this document under the terms of the GNU Free Documentation
    License, Version 1.3 or any later version published by the Free
    Software Foundation; with no Invariant Sections, no Front-Cover
    Texts, and no Back-Cover Texts.  A copy of the license can be
    found at the following
    location: <ulink url="http://www.gnu.org/licenses/fdl.html">GNU
          web site</ulink>.</literal></para>

      <para>This document introduces full text search notions
      and describes the installation and use of the &RCL;
      application. This version describes &RCL; &RCLVERSION;.</para>
    </abstract>


  </bookinfo>
  
  <chapter id="RCL.INTRODUCTION">
    <title>Introduction</title>

    <sect1 id="RCL.INTRODUCTION.TRYIT">
      <title>Giving it a try</title>
      
      <para>If you do not like reading manuals (who does?) but 
        wish to give &RCL; a try, just <link
        linkend="RCL.INSTALL.BINARY">install</link> the application
        and start the <command>recoll</command> graphical user
        interface (GUI), which will ask permission to index your home
        directory by default, allowing you to search immediately after
        indexing completes.</para>

      <para>Do not do this if your home directory contains a huge
        number of documents and you do not want to wait or are very
        short on disk space. In this case, you may first want to customize
        the <link linkend="RCL.INDEXING.CONFIG">configuration</link>
        to restrict the indexed area (for the very impatient with a completed package install, from the <command>recoll</command> GUI: <menuchoice>
	    <guimenu>Preferences</guimenu>
	    <guimenuitem>Indexing configuration</guimenuitem>
          </menuchoice>, then adjust the <guilabel>Top
          directories</guilabel> section).</para>

      <para>Also be aware that you may need to install the
        appropriate <link linkend="RCL.INSTALL.EXTERNAL"> supporting
        applications</link> for document types that need them (for
        example <application>antiword</application> for
        <application>Microsoft Word</application> files).</para>
    </sect1>

    <sect1 id="RCL.INTRODUCTION.SEARCH"> 
      <title>Full text search</title>

      <para>&RCL; is a full text search application. Full text search
        finds your data by content rather than by external attributes
        (like a file name). You specify words
        (terms) which should or should not appear in the text you are
        looking for, and receive in return a list of matching
        documents, ordered so that the most
        <emphasis>relevant</emphasis> documents will appear
        first.</para>

      <para>You do not need to remember in what file or email message you
        stored a given piece of information. You just ask for related
        terms, and the tool will return a list of documents where
        these terms are prominent, in a similar way to Internet search
        engines.</para>

      <para>Full text search applications try to determine which
        documents are most relevant to the search terms you
        provide. Computer algorithms for determining relevance can be
        very complex, and in general are inferior to the power of the
        human mind to rapidly determine relevance. The quality of
        relevance guessing is probably the most important aspect when
        evaluating a search application.</para>

        <para>In many cases, you are looking for all the forms of a
        word, including plurals, different tenses for a verb, or terms
        derived from the same root or <emphasis>stem</emphasis>
        (example: <replaceable>floor, floors, floored,
        flooring...</replaceable>). Queries are usually automatically
        expanded to all such related terms (words that reduce to the
        same stem). This can be prevented for searching for a specific
        form.</para>

        <para>Stemming, by itself, does not accommodate for misspellings
        or phonetic searches. A full text search application may also
        support this form of approximation. For example, a search for
        <replaceable>aliterattion</replaceable> returning no result may
        propose, depending on index contents, <replaceable>alliteration
        alteration alterations altercation</replaceable> as possible
        replacement terms. </para>

    </sect1>

      <sect1 id="RCL.INTRODUCTION.RECOLL">
      <title>Recoll overview</title>

      <para>&RCL; uses the 
      <ulink url="http://www.xapian.org">&XAP;</ulink> information retrieval
      library as its storage and retrieval engine. &XAP; is a very
      mature package using <ulink
      url="http://www.xapian.org/docs/intro_ir.html">a sophisticated
      probabilistic ranking model</ulink>.</para>
      
      <para>The &XAP; library manages an index database which
      describes where terms appear in your document files. It
      efficiently processes the complex queries which are produced by
      the &RCL; query expansion mechanism, and is in charge of the
      all-important relevance computation task.</para>

      <para>&RCL; provides the mechanisms and interface to get data
      into and out of the index. This includes translating the many
      possible document formats into pure text, handling term
      variations (using &XAP; stemmers), and spelling approximations
      (using the <application>aspell</application> speller),
      interpreting user queries and presenting results.</para>

      <para>In a shorter way, &RCL; does the dirty footwork, &XAP;
      deals with the intelligent parts of the process.</para>

      <para>The &XAP; index can be big (roughly the size of the
        original document set), but it is not a document
        archive. &RCL; can only display documents that still exist at
        the place from which they were indexed. (Actually, there is a
        way to reconstruct a document from the information in the
        index, but the result is not nice, as all formatting,
        punctuation and capitalization are lost).</para>

      <para>&RCL; stores all internal data in <application>Unicode
      UTF-8</application> format, and it can index files of many types
      with different character sets, encodings, and languages into the
      same index. It can process documents embedded inside other
      documents (for example a pdf document stored inside a Zip
      archive sent as an email attachment...), down to an arbitrary
      depth.</para>
      
      <para>Stemming is the process by which &RCL; reduces words to
        their radicals so that searching does not depend, for example, on a
        word being singular or plural (floor, floors), or on a verb tense
        (flooring, floored). Because the mechanisms used for stemming
        depend on the specific grammatical rules for each language, there
        is a separate &XAP; stemmer module for most common languages where
        stemming makes sense.</para>

      <para>&RCL; stores the unstemmed versions of terms in the main index
        and uses auxiliary databases for term expansion (one for each
        stemming language), which means that you can switch stemming
        languages between searches, or add a language without needing a
        full reindex.</para>

      <para>Storing documents written in different languages in the same
        index is possible, and commonly done. In this situation, you can
        specify several stemming languages for the index. </para>

      <para>&RCL; currently makes no attempt at automatic language
        recognition, which means that the stemmer will sometimes be applied
        to terms from other languages with potentially strange results. In
        practise, even if this introduces possibilities of confusion, this
        approach has been proven quite useful, and it is much less
        cumbersome than separating your documents according to what
        language they are written in.</para>

      <para>Before version 1.18, &RCL; stripped most accents and
        diacritics from terms, and converted them to lower case before
        either storing them in the index or searching for them. As a
        consequence, it was impossible to search for a particular
        capitalization of a term (<literal>US</literal> /
        <literal>us</literal>), or to discriminate two terms based on
        diacritics (<literal>sake</literal> / <literal>saké</literal>, 
        <literal>mate</literal> / <literal>maté</literal>).</para>
      
      <para>As of version 1.18, &RCL; can optionally store the raw terms,
        without accent stripping or case conversion. In this configuration,
        it is still possible (and most common) for a query to be
        insensitive to case and/or diacritics. Appropriate term expansions
        are performed before actually accessing the main index. This is
        described in more detail in the <link
        linkend="RCL.INDEXING.CONFIG.SENS">section about index case and
        diacritics sensitivity</link>.</para>

      <para>&RCL; has many parameters which define exactly what to
        index, and how to classify and decode the source
        documents. These are kept in <link
        linkend="RCL.INDEXING.CONFIG">configuration files</link>. A
        default configuration is copied into a standard location
        (usually something like
        <filename>/usr/[local/]share/recoll/examples</filename>)
        during installation. The default values set by the
        configuration files in this directory may be overridden by
        values that you set inside your personal configuration, found
        by default in the <filename>.recoll</filename> sub-directory
        of your home directory.  The default configuration will index
        your home directory with default parameters and should be
        sufficient for giving &RCL; a try, but you may want to adjust
        it later, which can be done either by editing the text files
        or by using configuration menus in the
        <command>recoll</command> GUI. Some other parameters affecting only
        the <command>recoll</command> GUI are stored in the standard
        location defined by <application>Qt</application>.</para>

      <para>The <link linkend="RCL.INDEXING.PERIODIC.EXEC">indexing
          process</link> is started automatically the first time you
        execute the <command>recoll</command> GUI. Indexing can also
        be performed by executing the <command>recollindex</command>
        command. &RCL; indexing is multithreaded by default when
        appropriate hardware resources are available, and can perform
        in parallel multiple tasks among text extraction, segmentation
        and index updates.</para>

      <para><link linkend="RCL.SEARCH">Searches</link> are usually
        performed inside the <command>recoll</command> GUI, which has many
        options to help you find what you are looking for. However, there
        are other ways to perform &RCL; searches: mostly a <link
        linkend="RCL.SEARCH.COMMANDLINE">
          command line interface</link>, a 
        <link linkend="RCL.PROGRAM.API.PYTHON">
          <application>Python</application>
          programming interface</link>, a <link linkend="RCL.SEARCH.KIO">
          <application>KDE</application> KIO slave module</link>, and
        Ubuntu Unity <ulink url="https://bitbucket.org/medoc/unity-lens-recoll">
        Lens</ulink> (for older versions) or 
        <ulink url="https://bitbucket.org/medoc/unity-scope-recoll">
          Scope</ulink> (for current versions) modules.
        </para>

    </sect1>
  </chapter>


  <chapter id="RCL.INDEXING">
    <title>Indexing</title>

    <sect1 id="RCL.INDEXING.INTRODUCTION">
      <title>Introduction</title>

      <para>Indexing is the process by which the set of documents is
	analyzed and the data entered into the database. &RCL;
	indexing is normally incremental: documents will only be
	processed if they have been modified since the last run. On
	the first execution, all documents will need processing. A
	full index build can be forced later by specifying an option
	to the indexing command (<command>recollindex</command>
	<option>-z</option> or <option>-Z</option>).</para>

      <para><command>recollindex</command> skips files which caused an
      error during a previous pass. This is a performance
      optimization, and a new behaviour in version 1.21 (failed files
      were always retried by previous versions). The command line
      option <option>-k</option> can be set to retry failed files, for
      example after updating a filter.</para>

      <para>The following sections give an overview of different
	aspects of the indexing processes and configuration, with links
	to detailed sections.</para>

	<para>Depending on your data, temporary files may be needed during
	indexing, some of them possibly quite big. You can use the
	<envar>RECOLL_TMPDIR</envar> or <envar>TMPDIR</envar> environment
	variables to determine where they are created (the default is to
	use <filename>/tmp</filename>). Using <envar>TMPDIR</envar> has
	the nice property that it may also be taken into account by 
	auxiliary commands executed by <command>recollindex</command>.</para>

      <sect2 id="RCL.INDEXING.INTRODUCTION.MODES">
	<title>Indexing modes</title> 

	<para>&RCL; indexing can be performed along two different modes:
	  <itemizedlist>
            <listitem>
              <formalpara>
		<title><link linkend="RCL.INDEXING.PERIODIC">
		    Periodic (or batch) indexing:</link></title>
		<para>indexing takes place at discrete
		  times, by executing the <command>recollindex</command>
		  command. The typical usage is to have a nightly indexing run 
		  <link linkend="RCL.INDEXING.PERIODIC.AUTOMAT">
		    programmed</link> into
		    your <command>cron</command> file.</para>
              </formalpara>
            </listitem>
            <listitem>
              <formalpara><title><link linkend="RCL.INDEXING.MONITOR">Real
		    time indexing:</link></title> 
		<para>indexing takes place as soon as a file is created or
		  changed. <command>recollindex</command> runs as a daemon
		  and uses a file system alteration monitor such as 
		  <application>inotify</application>, 
		  <application>Fam</application> or
		  <application>Gamin</application>
		  to detect file changes.</para>
              </formalpara>
            </listitem>
	  </itemizedlist>
	</para>
	<para>The choice between the two methods is mostly a matter of
          preference, and they can be combined by setting up multiple
          indexes (ie: use periodic indexing on a big documentation
          directory, and real time indexing on a small home
          directory). Monitoring a big file system tree can consume
          significant system resources.</para>

        <para>The choice of method and the parameters used can be
        configured from the <command>recoll</command> GUI:
	  <menuchoice>
	    <guimenu>Preferences</guimenu>
	    <guimenuitem>Indexing schedule</guimenuitem>
          </menuchoice>
         </para>
	</sect2>

      <sect2 id="RCL.INDEXING.INTRODUCTION.CONFIG">
	<title>Configurations, multiple indexes</title>
	
	<para>The parameters describing what is to be indexed and
	  local preferences are defined in text files contained in a
	  <link linkend="RCL.INDEXING.CONFIG">configuration
	  directory</link>.</para>

	<para>All parameters have defaults, defined in system-wide
	  files.</para> 

	<para>Without further configuration, &RCL; will index all
          appropriate files from your home directory, with a reasonable
          set of defaults.</para>

	<para>A default personal configuration directory
	  (<filename>$HOME/.recoll/</filename>) is created
	  when a &RCL; program is first executed. It is possible to
	  create other configuration directories, and use them by
	  setting the <envar>RECOLL_CONFDIR</envar> environment
	  variable, or giving the <option>-c</option> option to any of
	  the &RCL; commands.</para>

	<para>In some cases, it may be interesting to index different
	  areas of the file system to separate databases. You can do this
	  by using multiple configuration directories, each indexing a
	  file system area to a specific database. Typically, this
	  would be done to separate personal and shared
          indexes, or to take advantage of the organization of your data
          to improve search precision.</para>

	<para>The generated indexes can
          be queried concurrently in a transparent manner.</para>

	<para>For index generation, multiple configurations are
          totally independant from each other. When multiple indexes need
          to be used for a single search,
	  <link linkend="RCL.INDEXING.CONFIG.MULTIPLE">some parameters
          should be consistent among the configurations</link>.</para>

      </sect2>

      <sect2>
	<title>Document types</title>
	<para>&RCL; knows about quite a few different document
          types. The parameters for document types recognition and
          processing are set in 
          <link linkend="RCL.INDEXING.CONFIG">configuration files</link>.</para>

	<para>Most file types, like HTML or word processing files, only hold
          one document. Some file types, like email folders or zip
          archives, can hold many individually indexed documents, which may
          themselves be compound ones. Such hierarchies can go quite
          deep, and &RCL; can process, for example, a
          <application>LibreOffice</application> 
          document stored as an attachment to an email message inside an
          email folder archived in a zip file...</para>

	<para>&RCL; indexing processes plain text, HTML, OpenDocument
          (Open/LibreOffice), email formats, and a few others internally.</para>

	<para>Other file types (ie: postscript, pdf, ms-word, rtf ...) 
          need external applications for preprocessing. The list is in the
          <link linkend="RCL.INSTALL.EXTERNAL"> installation</link>
          section. After every indexing operation, &RCL; updates a list of
          commands that would be needed for indexing existing files
          types. This list can be displayed by selecting the menu option
	  <menuchoice>
	    <guimenu>File</guimenu>
	    <guimenuitem>Show Missing Helpers</guimenuitem>
          </menuchoice>
          in the <command>recoll</command> GUI. It is stored in the
          <filename>missing</filename> text file inside the configuration
          directory.</para>

        <para>By default, &RCL; will try to index any file type that
          it has a way to read. This is sometimes not desirable, and
          there are ways to either exclude some types, or on the
          contrary to define a positive list of types to be
          indexed. In the latter case, any type not in the list will
          be ignored.</para>

        <para>Excluding types can be done by adding wildcard name
          patterns to the <literal>skippedNames</literal> list, which
          can be done from the GUI Index configuration menu. For
          versions 1.20 and later, you can alternatively set the
          <literal>excludedmimetypes</literal> list in the
          configuration file. This can be redefined for
          subdirectories.</para>

        <para>You can also define an exclusive list of MIME types to be indexed (no others will be indexed), by settting
            the <literal>indexedmimetypes</literal> configuration
            variable. Example:<programlisting>
indexedmimetypes = text/html application/pdf
          </programlisting>
          It is possible to redefine this parameter for
          subdirectories. Example:<programlisting>
[/path/to/my/dir]
indexedmimetypes = application/pdf
          </programlisting>
          (When using sections like this, don't forget that they remain
          in effect until the end of the file or another section
          indicator).</para>

          <para><literal>excludedmimetypes</literal> or
          <literal>indexedmimetypes</literal>, can be set either by
          editing the <link linkend="RCL.INSTALL.CONFIG.RECOLLCONF">
          main configuration file
          (<filename>recoll.conf</filename>)</link>, or from the GUI
          index configuration tool.</para>


      </sect2>

      <sect2>
	<title>Indexing failures</title>

        <para>Indexing may fail for some documents, for a number of
        reasons: a helper program may be missing, the document may be
        corrupt, we may fail to uncompress a file because no file
        system space is available, etc.</para>
        
        <para>&RCL; versions prior to 1.21 always retried to index
        files which had previously caused an error. This guaranteed
        that anything that may have become indexable (for example
        because a helper had been installed) would be indexed. However
        this was bad for performance because some indexing failures
        may be quite costly (for example failing to uncompress a big
        file because of insufficient disk space).</para>

        <para>The indexer in &RCL; versions 1.21 and later do not
        retry failed file by default. Retrying will only occur if an
        explicit option (<option>-k</option>) is set on the
        <command>recollindex</command> command line, or if a script
        executed when <command>recollindex</command> starts up says
        so. The script is defined by a configuration variable
        (<literal>checkneedretryindexscript</literal>), and makes a
        rather lame attempt at deciding if a helper command may have
        been installed, by checking if any of the common
        <filename>bin</filename> directories have changed.</para>

      </sect2>

      <sect2>
	<title>Recovery</title>
	<para>In the rare case where the index becomes corrupted (which can
	  signal itself by weird search results or crashes), the index files
	  need to be erased before restarting a clean indexing pass. Just delete
	  the <filename>xapiandb</filename> directory (see 
	  <link linkend="RCL.INDEXING.STORAGE">next section</link>), or, 
	  alternatively, start the next <command>recollindex</command> with the 
	  <option>-z</option> option, which will reset the database before
	  indexing.</para>
      </sect2>

    </sect1>

    <sect1 id="RCL.INDEXING.STORAGE">
      <title>Index storage</title>

      <para>The default location for the index data is the
      <filename>xapiandb</filename> subdirectory of the &RCL;
      configuration directory, typically
      <filename>$HOME/.recoll/xapiandb/</filename>. This can be
      changed via two different methods (with different purposes):
      <itemizedlist>
          <listitem><para>You can specify a different configuration
          directory by setting the <envar>RECOLL_CONFDIR</envar>
          environment variable, or using the <option>-c</option>
          option to the &RCL; commands. This method would typically be
          used to index different areas of the file system to
          different indexes. For example, if you were to issue the
          following commands: 
          <programlisting>
export RECOLL_CONFDIR=~/.indexes-email
recoll
          </programlisting> Then &RCL; would use configuration files
          stored in <filename>~/.indexes-email/</filename> and,
          (unless specified otherwise in
          <filename>recoll.conf</filename>) would look for 
          the index in
          <filename>~/.indexes-email/xapiandb/</filename>.</para>

          <para>Using multiple configuration directories and <link
          linkend="RCL.INSTALL.CONFIG.RECOLLCONF">configuration
          options</link> allows you to tailor multiple configurations and
          indexes to handle whatever subset of the available data you wish
          to make searchable.</para>

          </listitem>

          <listitem><para>For a given configuration directory, you can
          specify a non-default storage location for the index by setting
          the <varname>dbdir</varname> parameter in the configuration file
          (see the <link
          linkend="RCL.INSTALL.CONFIG.RECOLLCONF">configuration
          section</link>). This method would mainly be of use if you wanted
          to keep the configuration directory in its default location, but
          desired another location for the index, typically out of disk
          occupation concerns.</para>
          </listitem>

        </itemizedlist>
      </para>

      <para>The size of the index is determined by the size of the set
        of documents, but the ratio can vary a lot. For a typical
        mixed set of documents, the index size will often be close to
        the data set size. In specific cases (a set of compressed mbox
        files for example), the index can become much bigger than the
        documents. It may also be much smaller if the documents
        contain a lot of images or other non-indexed data (an extreme
        example being a set of mp3 files where only the tags would be
        indexed).</para>

      <para>Of course, images, sound and video do not increase the
        index size, which means that nowadays (2012), typically, even a big
        index will be negligible against the total amount of data on the
        computer.</para>
      
      <para>The index data directory (<filename>xapiandb</filename>)
	only contains data that can be completely rebuilt by an index run
	(as long as the original documents exist), and it can always be
	destroyed safely.</para>

      <sect2 id="RCL.INDEXING.STORAGE.FORMAT">
        <title>&XAP; index formats</title>

        <para>&XAP; versions usually support several formats for index
          storage. A given major &XAP; version will have a current format,
          used to create new indexes, and will also support the format from
          the previous major version.</para>

        <para>&XAP; will not convert automatically an existing index
          from the older format to the newer one. If you want to upgrade to
          the new format, or if a very old index needs to be converted
          because its format is not supported any more, you will have to
          explicitly delete the old index, then run a normal indexing
          process.</para>

        <para>Using the <option>-z</option> option to
          <command>recollindex</command> is not sufficient to change the
          format, you will have to delete all files inside the index
          directory (typically <filename>~/.recoll/xapiandb</filename>)
          before starting the indexing.</para>

      </sect2>

      <sect2 id="RCL.INDEXING.STORAGE.SECURITY">
        <title>Security aspects</title>

        <para>The &RCL; index does not hold copies of the indexed
          documents. But it does hold enough data to allow for an almost
          complete reconstruction. If confidential data is indexed,
          access to the database directory should be restricted. </para>

        <para>&RCL; (since version 1.4) will create the configuration
          directory with a mode of 0700 (access by owner only). As the
          index data directory is by default a sub-directory of the
          configuration directory, this should result in appropriate
          protection.</para> 

        <para>If you use another setup, you should think of the kind
          of protection you need for your index, set the directory
          and files access modes appropriately, and also maybe adjust
          the <literal>umask</literal> used during index updates.</para>
        

      </sect2>

    </sect1>

    <sect1 id="RCL.INDEXING.CONFIG">
      <title>Index configuration</title>

      <para>Variables set inside the 
        <link linkend="RCL.INSTALL.CONFIG">&RCL; configuration files</link>
        control which areas of the file system are indexed, and how
        files are processed. These variables can be set either by
        editing the text files or by using the 
        <link linkend="RCL.INDEXING.CONFIG.GUI"> dialogs in the
        <command>recoll</command> GUI</link>.</para>

      <para>The first time you start <command>recoll</command>, you
        will be asked whether or not you would like it to build the
        index. If you want to adjust the configuration before
        indexing, just click <guilabel>Cancel</guilabel> at this
        point, which will get you into the configuration interface. If
        you exit at this point, <filename>recoll</filename> will have
        created a <filename>~/.recoll</filename> directory containing
        empty configuration files, which you can edit by hand.</para>

      <para>The configuration is documented inside the 
        <link linkend="RCL.INSTALL.CONFIG">installation chapter</link> 
        of this document, or in the 
       <citerefentry>
            <refentrytitle>recoll.conf</refentrytitle>
	    <manvolnum>5</manvolnum>
       </citerefentry>
        man page, but the most
        current information will most likely be the comments inside the
        sample file. The most immediately useful variable you may
        interested in is probably 
        <link linkend="RCL.INSTALL.CONFIG.RECOLLCONF.TOPDIRS">
	<varname>topdirs</varname></link>, 
        which determines what subtrees get indexed.</para>

      <para>The applications needed to index file types other than
        text, HTML or email (ie: pdf, postscript, ms-word...) are
        described in the <link linkend="RCL.INSTALL.EXTERNAL">external
          packages section.</link></para>

      <para>As of Recoll 1.18 there are two incompatible types of Recoll
      indexes, depending on the treatment of character case and
      diacritics. The next section describes the two types in more
      detail.</para>

      <sect2 id="RCL.INDEXING.CONFIG.MULTIPLE">
        <title>Multiple indexes</title>

        <para>Multiple &RCL; indexes can be created by
	using several configuration directories which are usually set to
	index different areas of the file system. A specific index can
	be selected for updating or searching, using the
	<envar>RECOLL_CONFDIR</envar> environment variable or the
	<option>-c</option> option to <command>recoll</command> and
	<command>recollindex</command>.</para>

        <para>A typical usage scenario for the multiple index feature
	would be for a system administrator to set up a central index
	for shared data, that you choose to search or not in addition to
	your personal data. Of course, there are other
	possibilities. There are many cases where you know the subset of
	files that should be searched, and where narrowing the search
	can improve the results. You can achieve approximately the same
	effect with the directory filter in advanced search, but
	multiple indexes will have much better performance and may be
	worth the trouble.</para>

        <para>A <command>recollindex</command> program instance can only
	update one specific index.</para>

        <para>The main index (defined by
	<envar>RECOLL_CONFDIR</envar> or <option>-c</option>) is
	always active. If this is undesirable, you can set up your
	base configuration to index an empty directory.</para>

        <para>The different search interfaces (GUI, command line, ...)
	have different methods to define the set of indexes to be
	used, see the appropriate section.</para>

        <para>If a set of multiple indexes are to be used together for
	searches, some configuration parameters must be consistent
	among the set. These are parameters which need to be the same
	when indexing and searching. As the parameters come from the
	main configuration when searching, they need to be compatible
	with what was set when creating the other indexes (which came
	from their respective configuration directories).</para>

        <para>Most importantly, all indexes to be queried concurrently must
        have the same option concerning character case and diacritics
        stripping, but there are other constraints. Most of the
	relevant parameters are described in the 
	<link linkend="RCL.INSTALL.CONFIG.RECOLLCONF.TERMS">linked
	section</link>.</para>

      </sect2>


      <sect2 id="RCL.INDEXING.CONFIG.SENS">
        <title>Index case and diacritics sensitivity</title>

        <para>As of &RCL; version 1.18 you have a choice of building an
          index with terms stripped of character case and diacritics, or
          one with raw terms. For a source term of
          <literal>Résumé</literal>, the former will store
          <literal>resume</literal>, the latter
          <literal>Résumé</literal>.</para>
        
        <para>Each type of index allows performing searches insensitive to
          case and diacritics: with a raw index, the user entry will be
          expanded to match all case and diacritics variations present in
          the index. With a stripped index, the search term will be stripped
          before searching.</para>
        
        <para>A raw index allows for another possibility which a stripped
          index cannot offer: using case and diacritics to discriminate
          between terms, returning different results when searching for
          <literal>US</literal> and <literal>us</literal> or
          <literal>resume</literal> and <literal>résumé</literal>.
          Read the <link linkend="RCL.SEARCH.CASEDIAC">section about search
          case and diacritics sensitivity</link> for more details.</para>

        <para>The type of index to be created is controlled by the
          <literal>indexStripChars</literal> configuration
          variable which can only be changed by editing the
          configuration file. Any change implies an index reset (not
          automated by &RCL;), and all indexes in a search must be set
          in the same way (again, not checked by &RCL;). </para>

        <para>If the <literal>indexStripChars</literal> is not set, &RCL;
          1.18 creates a stripped index by default, for
          compatibility with previous versions.</para>

        <para>As a cost for added capability, a raw index will be slightly
          bigger than a stripped one (around 10%). Also, searches will be
          more complex, so probably slightly slower, and the feature is
          still young, so that a certain amount of weirdness cannot be
          excluded.</para> 

        <para>One of the most adverse consequence of using a raw index
          is that some phrase and proximity searches may become
          impossible: because each term needs to be expanded, and all
          combinations searched for, the multiplicative expansion may
          become unmanageable.</para>

      </sect2>


      <sect2 id="RCL.INDEXING.CONFIG.GUI">
        <title>The index configuration GUI</title>

        <para>Most parameters for a given index configuration can
          be set from a <command>recoll</command> GUI running on this
          configuration (either as default, or by setting
          <envar>RECOLL_CONFDIR</envar> or the <option>-c</option>
          option.)</para> 

        <para>The interface is started from the
	<menuchoice>
            <guimenu>Preferences</guimenu>
	    <guimenuitem>Index Configuration</guimenuitem> 
	</menuchoice>
	menu entry. It is divided in four tabs,
        <guilabel>Global parameters</guilabel>, <guilabel>Local
        parameters</guilabel>, <guilabel>Web history</guilabel>
        (which is explained in the next section) and <guilabel>Search
        parameters</guilabel>.</para>

        <para>The <guilabel>Global parameters</guilabel> tab allows setting
        global variables, like the lists of top directories, skipped paths,
        or stemming languages.</para> 

        <para>The <guilabel>Local parameters</guilabel> tab allows setting
        variables that can be redefined for subdirectories. This second tab
        has an initially empty list of customisation directories, to which
        you can add. The variables are then set for the currently selected
        directory (or at the top level if the empty line is
        selected).</para>

        <para>The <guilabel>Search parameters</guilabel> section defines
          parameters which are used at query time, but are global to an
          index and affect all search tools, not only the GUI.</para>

        <para>The meaning for most entries in the interface is 
        self-evident and documented by a <literal>ToolTip</literal>
        popup on the text label. For more detail, you will need to
        refer to the <link linkend="RCL.INSTALL.CONFIG">configuration
        section</link> of this guide.</para>

        <para>The configuration tool normally respects the comments
        and most of the formatting inside the configuration file, so
        that it is quite possible to use it on hand-edited files,
        which you might nevertheless want to backup first...</para>

      </sect2>

    </sect1>

    <sect1 id="RCL.INDEXING.WEBQUEUE">
      <title>Indexing WEB pages you wisit</title>

      <para>With the help of a <application>Firefox</application>
      extension, &RCL; can index the Internet pages that you visit. The
      extension was initially designed for the
      <application>Beagle</application> indexer, but it has recently be
      renamed and better adapted to &RCL;.</para>

      <para>The extension works by copying visited WEB pages to an indexing
         queue directory, which &RCL; then processes, indexing the data,
         storing it into a local cache, then removing the file from the
         queue.</para>

      <para>This feature can be enabled in the GUI 
        <guilabel>Index configuration</guilabel>
	panel, or by editing the configuration file (set
	<varname>processwebqueue</varname> to 1).</para>

      <para>A current pointer to the extension can be found, along with
        up-to-date instructions, on the
        <ulink url="&WIKI;IndexWebHistory">Recoll wiki</ulink>.</para>

      <para>A copy of the indexed WEB pages is retained by Recoll in a
      local cache (from which previews can be fetched). The cache size can
      be adjusted from the <guilabel>Index configuration</guilabel> /
      <guilabel>Web history</guilabel> panel. Once the maximum size
      is reached, old pages are purged - both from the cache and the index
      - to make room for new ones, so you need to explicitly archive in
        some other place the pages that you want to keep
        indefinitely.</para> 

    </sect1>

    <sect1 id="RCL.INDEXING.EXTATTR">
      <title>Extended attributes data</title>

      <para>User extended attributes are named pieces of information
        that most modern file systems can attach to any file.</para>

      <para>&RCL; versions 1.19 and later process extended attributes
        as document fields by default. For older versions, this has to
        be activated at build time.</para>

      <para>A 
        <ulink url="http://www.freedesktop.org/wiki/CommonExtendedAttributes">
          freedesktop standard</ulink> defines a few special
          attributes, which are handled as such by &RCL;:
        <variablelist>
          <varlistentry>
            <term>mime_type</term>
            <listitem><para>If set, this overrides any other
                determination of the file MIME type.</para></listitem>
          </varlistentry>
          <varlistentry>
            <term>charset</term>
            <listitem>If set, this defines the file character set
              (mostly useful for plain text files).</listitem>
          </varlistentry>
        </variablelist>
      </para>

      <para>By default, other attributes are handled as &RCL; fields.
        On Linux, the <literal>user</literal> prefix is removed from
        the name. This can be configured more precisely inside
        the <link linkend="RCL.INSTALL.CONFIG.FIELDS">
          <filename>fields</filename> configuration file</link>.
      </para>

    </sect1>

    <sect1 id="RCL.INDEXING.EXTTAGS">
      <title>Importing external tags</title>

      <para>During indexing, it is possible to import metadata for
        each file by executing commands. For example, this could
        extract user tag data for the file and store it in a field for
        indexing.</para>

      <para>See the 
        <link linkend="RCL.INSTALL.CONFIG.RECOLLCONF.METADATACMDS">section
          about the <literal>metadatacmds</literal> field</link> in
        the main configuration chapter for more detail.</para>

    </sect1>

    <sect1 id="RCL.INDEXING.PERIODIC">
      <title>Periodic indexing</title>

      <sect2 id="RCL.INDEXING.PERIODIC.EXEC">
        <title>Running indexing</title>

        <para>Indexing is always performed by the
          <command>recollindex</command> program, which can be started
          either from the command line or from the <guimenu>File</guimenu>
          menu in the <command>recoll</command> GUI program. When started
          from the GUI, the indexing will run on the same configuration
          <command>recoll</command> was started on. When started from the
          command line, <command>recollindex</command> will use the
          <envar>RECOLL_CONFDIR</envar> variable or accept a
          <option>-c</option> <replaceable>confdir</replaceable> option
          to specify a non-default configuration directory.</para>

        <para>If the <command>recoll</command> program finds no index
          when it starts, it will automatically start indexing (except
          if canceled).</para>

        <para>The <command>recollindex</command> indexing process can be
          interrupted by sending an interrupt (<keysym>Ctrl-C</keysym>, 
	  SIGINT) or terminate
          (SIGTERM) signal. Some time may elapse before the process exits,
          because it needs to properly flush and close the index. This can
          also be done from the <command>recoll</command> GUI
	  <menuchoice>
	        <guimenu>File</guimenu>
                <guimenuitem>Stop Indexing</guimenuitem>
          </menuchoice>
          menu entry.</para>

	<para>After such an interruption, the index will be somewhat
	  inconsistent because some operations which are normally
	  performed at the end of the indexing pass will have been
	  skipped (for example, the stemming and spelling databases
	  will be inexistant or out of date). You just need to restart
	  indexing at a later time to restore consistency. The
	  indexing will restart at the interruption point (the full
	  file tree will be traversed, but files that were indexed up
	  to the interruption and for which the index is still up to
	  date will not need to be reindexed).</para>

        <para><command>recollindex</command> has a number of other options
          which are described in its man page. Only a few will be
          described here.</para>
	<para>Option <option>-z</option> will reset the index when
	  starting. This is almost the same as destroying the index
	  files (the nuance is that the &XAP; format version will not
	  be changed).</para>
	<para>Option <option>-Z</option> will force the update of all
	  documents without resetting the index first. This will not
	  have the "clean start" aspect of <option>-z</option>, but
	  the advantage is that the index will remain available for
	  querying while it is rebuilt, which can be a significant
	  advantage if it is very big (some installations need days
	  for a full index rebuild).</para>

        <para>Option <option>-k</option> will force retrying files
          which previously failed to be indexed, for example because
          of a missing helper program.</para>

        <para>Of special interest also, maybe, are
          the <option>-i</option> and <option>-f</option>
          options. <option>-i</option> allows indexing an explicit
          list of files (given as command line parameters or read on
          <literal>stdin</literal>).  <option>-f</option> tells
          <command>recollindex</command> to ignore file selection
          parameters from the configuration. Together, these options
          allow building a custom file selection process for some area
          of the file system, by adding the top directory to the
          <varname>skippedPaths</varname> list and using an
          appropriate file selection method to build the file list to
          be fed to <command>recollindex</command>
          <option>-if</option>.  Trivial example:</para>

	  <programlisting>
	    find . -name indexable.txt -print | recollindex -if
	  </programlisting>

        <para><command>recollindex</command> <option>-i</option> will 
	  not descend into subdirectories specified as parameters, 
	  but just add them as index entries. It is
          up to the external file selection method to build the complete
          file list.</para>
      </sect2>

      <sect2 id="RCL.INDEXING.PERIODIC.AUTOMAT">
        <title>Using <command>cron</command> to automate
          indexing</title>

        <para>The most common way to set up indexing is to have a cron
          task execute it every night. For example the following
          <filename>crontab</filename> entry would do it every day at
          3:30AM (supposing <command>recollindex</command> is in your
          PATH):

        <screen><![CDATA[
30 3 * * * recollindex > /some/tmp/dir/recolltrace 2>&1
]]></screen>

	  Or, using <command>anacron</command>:
<screen><![CDATA[
1  15  su mylogin -c "recollindex recollindex > /tmp/rcltraceme 2>&1"
]]></screen>
        </para>

        <para>As of version 1.17 the &RCL; GUI has dialogs to manage
          <filename>crontab</filename> entries for
          <command>recollindex</command>. You can reach them from the
	  <menuchoice>
              <guimenu>Preferences</guimenu>
	      <guimenuitem>Indexing Schedule</guimenuitem> 
          </menuchoice> 
	  menu. They only 
          work with the good old <command>cron</command>, and do not give
          access to all features of <command>cron</command> scheduling.</para>

        <para>The usual command to edit your
          <filename>crontab</filename> is <command>crontab</command>
          <option>-e</option> (which will usually start the
          <command>vi</command> editor to edit the file). You may have
          more sophisticated tools available on your system.</para>

        <para>Please be aware that there may be differences between your
          usual interactive command line environment and the one seen by
          crontab commands. Especially the PATH variable may be of
          concern. Please check the crontab manual pages about possible
          issues.</para>


      </sect2>
    </sect1>

    <sect1 id="RCL.INDEXING.MONITOR">
      <title>Real time indexing</title>

      <para>Real time monitoring/indexing is performed by starting the
        <command>recollindex</command> <option>-m</option> command.
        With this option, <command>recollindex</command> will detach
        from the terminal and become a daemon, permanently monitoring
        file changes and updating the index.</para>

      <para>Under <application>KDE</application>,
      <application>Gnome</application> and some other desktop
      environments, the daemon can automatically started when you log
      in, by creating a desktop file inside the
      <filename>~/.config/autostart</filename> directory.  This can be
      done for you by the &RCL; GUI. Use the
      <guimenu>Preferences->Indexing Schedule</guimenu> menu.</para>
      
      <para>With older <application>X11</application> setups, starting
        the daemon is normally performed as part of the user session
        script.</para>

      <para>The <filename>rclmon.sh</filename> script can be used to
      easily start and stop the daemon. It can be found in the
      <filename>examples</filename> directory (typically
      <filename>/usr/local/[share/]recoll/examples</filename>).</para>

      <para>For example, my out of fashion
        <application>xdm</application>-based session has a
        <filename>.xsession</filename> script with the following lines
        at the end:</para>

      <programlisting>recollconf=$HOME/.recoll-home
recolldata=/usr/local/share/recoll
RECOLL_CONFDIR=$recollconf $recolldata/examples/rclmon.sh start

fvwm 

</programlisting>

      <para>The indexing daemon gets started, then the window manager,
        for which the session waits.</para> <para>By default the
        indexing daemon will monitor the state of the X11 session, and
        exit when it finishes, it is not necessary to kill it
        explicitly. (The <application>X11</application> server
        monitoring can be disabled with option <option>-x</option> to
        <command>recollindex</command>).</para>

      <para>If you use the daemon completely out of an
        <application>X11</application> session, you need to add option
        <option>-x</option> to disable <application>X11</application>
        session monitoring (else the daemon will not start).</para>

      <para>By default, the messages from the indexing daemon will be
        setn to the same file as those from the interactive commands
        (<literal>logfilename</literal>).  You may want to change this
        by setting the <varname>daemlogfilename</varname> and
        <varname>daemloglevel</varname> configuration parameters. Also
        the log file will only be truncated when the daemon starts. If
        the daemon runs permanently, the log file may grow quite big,
        depending on the log level.</para>

      <para>When building &RCL;, the real time indexing support can be
        customised during package <link
        linkend="RCL.INSTALL.BUILDING.BUILD">configuration</link> with
        the <option>--with[out]-fam</option> or
        <option>--with[out]-inotify</option> options.  The default is
        currently to include <application>inotify</application>
        monitoring on systems that support it, and, as of &RCL; 1.17,
        <application>gamin</application> support on
        <application>FreeBSD</application>.</para>

      <para>While it is convenient that data is indexed in real time,
        repeated indexing can generate a significant load on the
        system when files such as email folders change. Also,
        monitoring large file trees by itself significantly taxes
        system resources. You probably do not want to enable it if
        your system is short on resources. Periodic indexing is
        adequate in most cases.</para>

      <note><title>Increasing resources for inotify</title>
	<para>On Linux systems, monitoring a big tree may need
	  increasing the resources available to inotify, which are
	  normally defined in <filename>/etc/sysctl.conf</filename>.
	  <programlisting>
### inotify
#
# cat  /proc/sys/fs/inotify/max_queued_events   - 16384
# cat  /proc/sys/fs/inotify/max_user_instances  - 128
# cat  /proc/sys/fs/inotify/max_user_watches    - 16384
#
# -- Change to:
#
fs.inotify.max_queued_events=32768
fs.notify.max_user_instances=256
fs.inotify.max_user_watches=32768
	  </programlisting>
    
	</para>
        <para>Especially, you will need to trim your tree or adjust
        the <literal>max_user_watches</literal> value if indexing exits with
        a message about errno <literal>ENOSPC</literal> (28) from
          <function>inotify_add_watch</function>.</para>
      </note>

      <sect2 id="RCL.INDEXING.MONITOR.FASTFILES">
        <title>Slowing down the reindexing rate for fast changing
        files</title>

        <para>When using the real time monitor, it may happen that some
        files need to be indexed, but change so often that they impose an
        excessive load for the system.</para>

        <para>&RCL; provides a configuration option to specify the minimum
        time before which a file, specified by a wildcard pattern, cannot be
        reindexed. See the <varname>mondelaypatterns</varname> parameter in
        the <link linkend="RCL.INSTALL.CONFIG.RECOLLCONF.MISC">
         configuration section</link>.</para>

      </sect2>
    </sect1>

  </chapter>

  <chapter id="RCL.SEARCH">
    <title>Searching</title>

  <sect1 id="RCL.SEARCH.GUI">
    <title>Searching with the Qt graphical user interface</title>

    <para>The <command>recoll</command> program provides the main user
      interface for searching. It is based on the
      <application>Qt</application> library.</para>

    <para><command>recoll</command> has two search modes:</para>
    <itemizedlist>
      <listitem><para>Simple search (the default, on the main screen) has
        a single entry field where you can enter multiple words.</para>
      </listitem>
      <listitem><para>Advanced search (a panel accessed through the
        <guilabel>Tools</guilabel> menu or the toolbox bar icon) has
        multiple entry fields, which you may use to build a logical
        condition, with additional filtering on file type, location
        in the file system, modification date, and size.</para>
      </listitem>
    </itemizedlist>

    <para>In most cases, you can enter the terms as you
        think them, even if they contain embedded punctuation or other
        non-textual characters. For
        example, &RCL; can handle things like email addresses, or
        arbitrary cut and paste from another text window, punctation
        and all.</para>

    <para>The main case where you should enter text differently from
      how it is printed is for east-asian languages (Chinese,
      Japanese, Korean). Words composed of single or multiple
      characters should be entered separated by white space in this
      case (they would typically be printed without white
      space).</para>

      <para>Some searches can be quite complex, and you may want to
      re-use them later, perhaps with some tweaking. &RCL; versions
      1.21 and later can save and restore searches, using XML files. See 
      <link linkend="RCL.SEARCH.SAVING">Saving and restoring 
      queries</link>.</para>

    <sect2 id="RCL.SEARCH.GUI.SIMPLE">
      <title>Simple search</title>

      <procedure>
        <step><para>Start the <command>recoll</command> program.</para>
        </step>
        <step><para>Possibly choose a search mode: <guilabel>Any
        term</guilabel>, <guilabel>All terms</guilabel>, 
        <guilabel>File name</guilabel> or
        <guilabel>Query language</guilabel>.</para>
        </step>
        <step><para>Enter search term(s) in the text field at the top of the
        window.</para>
        </step>
        <step><para>Click the <guilabel>Search</guilabel> button or
        hit the <keycap>Enter</keycap> key to start the search.</para>
        </step>
      </procedure>

      <para>The initial default search mode is <guilabel>Query
        language</guilabel>. Without special directives, this will look for
        documents containing all of the search terms (the ones with more
        terms will get better scores), just like the <guilabel>All
        terms</guilabel> mode which will ignore such
        directives. <guilabel>Any term</guilabel> will search for documents
        where at least one of the terms appear. </para>

      <para>The <guilabel>Query Language</guilabel> features are
      described in <link linkend="RCL.SEARCH.LANG">a separate
      section</link>.</para>  

      <para>All search modes allow wildcards inside terms
        (<literal>*</literal>, <literal>?</literal>,
        <literal>[]</literal>). You may want to have a look at the
        <link linkend="RCL.SEARCH.WILDCARDS">section about wildcards</link>
        for more information about this.</para>

      <para><guilabel>File name</guilabel> will specifically look for file
        names. The point of having a separate file name
        search is that wild card expansion can be performed more
        efficiently on a small subset of the index (allowing
        wild cards on the left of terms without excessive penality).
        Things to know:
        <itemizedlist>
            <listitem><para>White space in the entry should match white
            space in the file name, and is not treated specially.</para>
            </listitem>
            <listitem><para>The search is insensitive to character case and
            accents, independantly of the type of index.</para>
            </listitem>
            <listitem><para>An entry without any wild card
            character and not capitalized will be prepended and appended
            with '*' (ie: <replaceable>etc</replaceable> ->
            <replaceable>*etc*</replaceable>, but
            <replaceable>Etc</replaceable> ->
            <replaceable>etc</replaceable>).</para> 
            </listitem>
            <listitem><para>If you have a big index (many files),
            excessively generic fragments may result in inefficient
            searches.</para>
            </listitem>
          </itemizedlist>
      </para>

      <para>You can search for exact phrases (adjacent words in a
      given order) by enclosing the input inside double quotes. Ex:
     <literal>"virtual reality"</literal>.</para>

      <para>When using a stripped index, character case has no influence on
      search, except that you can disable stem expansion for any term by
      capitalizing it. Ie: a search for <literal>floor</literal> will also
      normally look for <literal>flooring</literal>,
      <literal>floored</literal>, etc., but a search for
      <literal>Floor</literal> will only look for <literal>floor</literal>,
      in any character case. Stemming can also be disabled globally in the
      preferences. When using a raw index, <link
      linkend="RCL.SEARCH.CASEDIAC">the rules are a bit more
      complicated</link>.</para> 

      <para>&RCL; remembers the last few searches that you
        performed. You can use the simple search text entry widget (a
        combobox) to recall them (click on the thing at the right of the
        text field). Please note, however, that only the search texts
        are remembered, not the mode (all/any/file name).</para>

      <para>Typing <keycap>Esc</keycap> <keycap>Space</keycap> while
        entering a word in the simple search entry will open a window
        with possible completions for the word. The completions are
        extracted from the database.</para>

      <para>Double-clicking on a word in the result list or a preview
      window will insert it into the simple search entry field.</para>

      <para>You can cut and paste any text into an <guilabel>All
      terms</guilabel> or <guilabel>Any term</guilabel> search field,
      punctuation, newlines and all - except for wildcard characters
      (single <literal>?</literal> characters are ok). &RCL; will process
      it and produce a meaningful search. This is what most differentiates
      this mode from the <guilabel>Query Language</guilabel> mode, where
      you have to care about the syntax.</para>

      <para>You can use the <link linkend="RCL.SEARCH.GUI.COMPLEX">
      <menuchoice>
          <guimenu>Tools</guimenu> 
          <guimenuitem>Advanced search</guimenuitem>
      </menuchoice>
      </link> dialog for more complex searches.</para>

    </sect2>

    <sect2 id="RCL.SEARCH.GUI.RESLIST">
      <title>The default result list</title>

      <para>After starting a search, a list of results will instantly
       be displayed in the main list window.</para> 

      <para>By default, the document list is presented in order of
       relevance (how well the system estimates that the document
       matches the query). You can sort the result by ascending or
       descending date by using the vertical arrows in the toolbar.</para>

      <para>Clicking on the
       <literal>Preview</literal> link for an entry will open an
       internal preview window for the document. Further
       <literal>Preview</literal> clicks for the same search will open
       tabs in the existing preview window. You can use
       <keycap>Shift</keycap>+Click to force the creation of another
       preview window, which may be useful to view the documents side
       by side. (You can also browse successive results in a single
       preview window by typing
       <keycap>Shift</keycap>+<keycap>ArrowUp/Down</keycap> in the
       window).</para> 

      <para>Clicking the <literal>Open</literal> link will
       start an external viewer for the document. By default, &RCL; lets
       the desktop choose the appropriate application for most document
       types (there is a short list of exceptions, see further). If you
       prefer to completely customize the choice of applications, you can
       uncheck the <guilabel>Use desktop preferences</guilabel> option in
       the GUI preferences dialog, and click the <guilabel>Choose editor
       applications</guilabel> button to adjust the predefined &RCL;
       choices. The tool accepts multiple selections of MIME types (e.g. to
       set up the editor for the dozens of office file types).</para>

        <para>Even when <guilabel>Use desktop preferences</guilabel> is
        checked, there is a small list of exceptions, for MIME types where
        the &RCL; choice should override the desktop one. These are
        applications which are well integrated with &RCL;, especially
        <application>evince</application> for viewing PDF and Postscript
        files because of its support for opening the document at a specific
        page and passing a search string as an argument. Of course, you can
        edit the list (in the GUI preferences) if you would prefer to lose
        the functionality and use the standard desktop tool.</para>

        <para>You may also change the choice of applications by editing the
       <link linkend="RCL.INSTALL.CONFIG.MIMEVIEW">
       <filename>mimeview</filename></link> configuration file if you find
       this more convenient.</para>

       <para>Each result entry also has a right-click menu with an
       <guilabel>Open With</guilabel> entry. This lets you choose an
       application from the list of those which registered with the desktop
       for the document MIME type.</para>

      <para>The <literal>Preview</literal> and <literal>Open</literal>
       edit links may not be present for all entries, meaning that
       &RCL; has no configured way to preview a given file type (which
       was indexed by name only), or no configured external editor for
       the file type. This can sometimes be adjusted simply by tweaking
       the <link linkend="RCL.INSTALL.CONFIG.MIMEMAP">
             <filename>mimemap</filename></link> and  
       <link linkend="RCL.INSTALL.CONFIG.MIMEVIEW">
       <filename>mimeview</filename></link> configuration files (the latter
       can be modified with the user preferences dialog).</para> 

      <para>The format of the result list entries is entirely
      configurable by using the preference dialog to 
      <link linkend="RCL.SEARCH.GUI.CUSTOM.RESLIST">edit an HTML
      fragment</link>.</para>

      <para>You can click on the <literal>Query details</literal> link
        at the top of the results page to see the query actually 
        performed, after stem expansion and other processing.</para>

      <para>Double-clicking on any word inside the result list or a
      preview window will insert it into the simple search text.</para>

      <para>The result list is divided into pages (the size of which
       you can change in the preferences). Use the arrow buttons in the
       toolbar or the links at the bottom of the page to browse the
       results.</para>

      <sect3 id="RCL.SEARCH.GUI.RESLIST.SUGGS">
          <title>No results: the spelling suggestions</title>

          <para>When a search yields no result, and if the
          <application>aspell</application> dictionary is configured, &RCL;
          will try to check for misspellings among the query terms, and
          will propose lists of replacements. Clicking on one of the
          suggestions will replace the word and restart the search. You can
          hold any of the modifier keys (Ctrl, Shift, etc.) while clicking
          if you would rather stay on the suggestion screen because several
          terms need replacement.</para>

        </sect3>


      <sect3 id="RCL.SEARCH.GUI.RESULTLIST.MENU">
        <title>The result list right-click menu</title>

        <para>Apart from the preview and edit links, you can display a
          pop-up menu by right-clicking over a paragraph in the result
         list. This menu has the following entries:</para>

        <itemizedlist>
          <listitem><para><guilabel>Preview</guilabel></para></listitem>
          <listitem><para><guilabel>Open</guilabel></para></listitem>
          <listitem><para><guilabel>Open With</guilabel></para></listitem>
          <listitem><para><guilabel>Run Script</guilabel></para></listitem>
          <listitem><para><guilabel>Copy File Name</guilabel></para></listitem>
          <listitem><para><guilabel>Copy Url</guilabel></para></listitem>
          <listitem><para><guilabel>Save to File</guilabel></para></listitem>
          <listitem><para><guilabel>Find similar</guilabel></para></listitem>
          <listitem><para><guilabel>Preview Parent
                document</guilabel></para></listitem> 
          <listitem><para><guilabel>Open Parent
                document</guilabel></para></listitem> 
          <listitem><para><guilabel>Open Snippets
                Window</guilabel></para></listitem>  
        </itemizedlist>

        <para>The <guilabel>Preview</guilabel> and
          <guilabel>Open</guilabel> entries do the same thing as the 
          corresponding links.</para>

        <para><guilabel>Open With</guilabel> lets you open the document
        with one of the applications claiming to be able to handle its MIME
        type (the information comes from the <literal>.desktop</literal>
        files in 
        <filename>/usr/share/applications</filename>).</para>

        <para><guilabel>Run Script</guilabel> allows starting an arbitrary
        command on the result file. It will only appear for results which
        are top-level files. See <link
            linkend="RCL.SEARCH.GUI.RUNSCRIPT">further</link> for a more
        detailed description.</para>

        <para>The <guilabel>Copy File Name</guilabel> and
        <guilabel>Copy Url</guilabel> copy the relevant data to the
        clipboard, for later pasting.</para> 

        <para><guilabel>Save to File</guilabel> allows saving the
        contents of a result document to a chosen file. This entry
        will only appear if the document does not correspond to an
        existing file, but is a subdocument inside such a file (ie: an
        email attachment). It is especially useful to extract attachments
        with no associated editor.</para> 

        <para>The <guilabel>Open/Preview Parent document</guilabel> entries
        allow working with the higher level document (e.g. the email
        message an attachment comes from). &RCL; is sometimes not totally
        accurate as to what it can or can't do in this area.  For example
        the <guilabel>Parent</guilabel> entry will also appear for an
        email which is part of an mbox folder file, but you can't actually
        visualize the mbox (there will be an error dialog if you
        try).</para>

        <para>If the document is a top-level file, <guilabel>Open
        Parent</guilabel> will start the default file manager on the
        enclosing filesystem directory.</para>

        <para>The <guilabel>Find similar</guilabel> entry will select
        a number of relevant term from the current document and enter
        them into the simple search field. You can then start a simple
        search, with a good chance of finding documents related to the
        current result. I can't remember a single instance where this
        function was actually useful to me...</para>

        <para id="RCL.SEARCH.GUI.RESULTLIST.MENU.SNIPPETS">The <guilabel>Open Snippets Window</guilabel> entry will only
        appear for documents which support page breaks (typically
        PDF, Postscript, DVI). The snippets window lists extracts from
        the document, taken around search terms occurrences, along with the
        corresponding page number, as links which can be used to start
        the native viewer on the appropriate page. If the viewer supports
        it, its search function will also be primed with one of the
        search terms.</para>

      </sect3>

    </sect2>

    <sect2 id="RCL.SEARCH.GUI.RESTABLE">
      <title>The result table</title>

        <para>In &RCL; 1.15 and newer, the results can be displayed in 
        spreadsheet-like fashion. You can switch to this presentation by
        clicking the table-like icon in the toolbar (this is a toggle,
        click again to restore the list).</para>

        <para>Clicking on the column headers will allow sorting by the
        values in the column. You can click again to invert the order, and
        use the header right-click menu to reset sorting to the default
        relevance order (you can also use the sort-by-date arrows to do
        this).</para>

        <para>Both the list and the table display the same underlying
          results. The sort order set from the table is still active if you
          switch back to the list mode. You can click twice on a date sort
          arrow to reset it from there.</para>

        <para>The header right-click menu allows adding or deleting
          columns. The columns can be resized, and their order can be changed
          (by dragging). All the changes are recorded when you quit
          <command>recoll</command></para> 
        
        <para>Hovering over a table row will update the detail area at the
        bottom of the window with the corresponding values. You can click
        the row to freeze the display. The bottom area is equivalent to a
        result list paragraph, with links for starting a preview or a
        native application, and an equivalent right-click menu. Typing
        <keycap>Esc</keycap> (the Escape key) will unfreeze the
        display.</para>

      </sect2>

    <sect2 id="RCL.SEARCH.GUI.RUNSCRIPT">
      <title>Running arbitrary commands on result files (1.20 and later)</title>

      <para>Apart from the <guilabel>Open</guilabel> and <guilabel>Open
      With</guilabel> operations, which allow starting an application on a
      result document (or a temporary copy), based on its MIME type, it is
      also possible to run arbitrary commands on results which are
      top-level files, using the <guilabel>Run Script</guilabel> entry in
      the results pop-up menu.</para>

      <para>The commands which will appear in the <guilabel>Run
      Script</guilabel> submenu must be defined by
      <literal>.desktop</literal> files inside the
      <filename>scripts</filename> subdirectory of the current
      configuration directory.</para>

      <para>Here follows an example of a <literal>.desktop</literal> file,
      which could be named for example,
      <filename>~/.recoll/scripts/myscript.desktop</filename> (the exact
      file name inside the directory is irrelevant):
      <programlisting>
[Desktop Entry]
Type=Application
Name=MyFirstScript
Exec=/home/me/bin/tryscript %F
MimeType=*/*
      </programlisting>
      The <literal>Name</literal> attribute defines the label which will
      appear inside the <guilabel>Run Script</guilabel> menu. The
      <literal>Exec</literal> attribute defines the program to be run,
      which does not need to actually be a script, of course. The
      <literal>MimeType</literal> attribute is not used, but needs to exist.
      </para>

      <para>The commands defined this way can also be used from links
      inside the <link linkend="RCL.SEARCH.GUI.CUSTOM.RESLIST.PARA">
      result paragraph</link>.</para>
      
      <para>As an example, it might make sense to write a script which
      would move the document to the trash and purge it from the &RCL;
      index.</para>

    </sect2>

     <sect2 id="RCL.SEARCH.GUI.THUMBNAILS">
          <title>Displaying thumbnails</title>

        <para>The default format for the result list entries and the
          detail area of the result table display an icon for each result
          document. The icon is either a generic one determined from the
          MIME type, or a thumbnail of the document appearance. Thumbnails
          are only displayed if found in the standard
          <application>freedesktop</application> location, where they would
          typically have been created by a file manager.</para>

        <para>Recoll has no capability to create thumbnails. A relatively
        simple trick is to use the <guilabel>Open parent
        document/folder</guilabel> entry in the result list popup
        menu. This should open a file manager window on the containing
        directory, which should in turn create the thumbnails (depending on
        your settings). Restarting the search should then display the
        thumbnails.</para>
        
        <para>There are also <ulink url="&WIKI;ResultsThumbnails.wiki">some
          pointers about  thumbnail generation</ulink> on the &RCL; wiki.
          </para>

      </sect2>

    <sect2 id="RCL.SEARCH.GUI.PREVIEW">
      <title>The preview window</title>

      <para>The preview window opens when you first click a
      <literal>Preview</literal> link inside the result list.</para>

      <para>Subsequent preview requests for a given search open new
      tabs in the existing window (except if you hold the
      <keycap>Shift</keycap> key while clicking which will open a new
      window for side by side viewing).</para>
      
      <para>Starting another search and requesting a preview will
      create a new preview window. The old one stays open until you
      close it.</para>

      <para>You can close a preview tab by typing <keycap>Ctrl-W</keycap> 
      (<keycap>Ctrl</keycap> + <keycap>W</keycap>) in the
      window. Closing the last tab for a window will also close the
      window.</para> 

      <para>Of course you can also close a preview window by using the
	window manager button in the top of the frame.</para>

      <para>You can display successive or previous documents from the
      result list inside a preview tab by typing
      <keycap>Shift</keycap>+<keycap>Down</keycap> or
      <keycap>Shift</keycap>+<keycap>Up</keycap> (<keycap>Down</keycap>
      and <keycap>Up</keycap> are the arrow keys).</para> 

      <para>A right-click menu in the text area allows switching
	between displaying the main text or the contents of fields
	associated to the document (ie: author, abtract, etc.). This is
	especially useful in cases where the term match did not occur in
	the main text but in one of the fields. In the case of
	images, you can switch between three displays: the image
	itself, the image metadata as extracted
	by <command>exiftool</command> and the fields, which is the
	metadata stored in the index.</para>


      <para>You can print the current preview window contents by typing
         <keycap>Ctrl-P</keycap> (<keycap>Ctrl</keycap> +
         <keycap>P</keycap>) in  the window text.</para> 


      <sect3 id="RCL.SEARCH.GUI.PREVIEW.SEARCH">
	<title>Searching inside the preview</title>

	<para>The preview window has an internal search capability,
	  mostly controlled by the panel at the bottom of the window,
	  which works in two modes: as a classical editor incremental
	  search, where we look for the text entered in the entry
	  zone, or as a way to walk the matches between the document
	  and the &RCL; query that found it.</para>

	<variablelist>
	  <varlistentry>
	    <term>Incremental text search</term>
	    <listitem><para>The preview tabs have an internal incremental search
		function. You initiate the search either by typing a
		<keycap>/</keycap> (slash) or <keycap>CTL-F</keycap>
		inside the text area or by clicking into
		the <guilabel>Search for:</guilabel> text field and
		entering the search string. You can then use the 
		<guilabel>Next</guilabel>
		and <guilabel>Previous</guilabel> buttons 
		to find the next/previous occurrence. You can also type
		<keycap>F3</keycap> inside the text area to get to the next
		occurrence.</para>
	      <para>If you have a search string entered and you use
		Ctrl-Up/Ctrl-Down to browse the results, the search is
		initiated for each successive document. If the string is
		found, the cursor will be positioned at the first
		occurrence of the search string.</para>
	    </listitem>
	  </varlistentry>

	  <varlistentry>
	    <term>Walking the match lists</term>
	    <listitem><para>If the entry area is empty when you click
		the <guilabel>Next</guilabel>
		or <guilabel>Previous</guilabel> buttons, the editor will
		be scrolled to show the next match to any search term
		(the next highlighted zone). If you select a search group
		from the dropdown list and click <guilabel>Next</guilabel>
		or <guilabel>Previous</guilabel>, the match list for this
		group will be walked. This is not the same as a text
		search, because the occurences will include non-exact
		matches (as caused by stemming or wildcards). The search
		will revert to the text mode as soon as you edit the
		entry area.</para></listitem>
	  </varlistentry>
	</variablelist>


      </sect3>        
        
    </sect2>

    <sect2 id="RCL.SEARCH.GUI.FRAGBUTS">
      <title>The Query Fragments window</title>

      <para>Selecting the <menuchoice><guimenu>Tools</guimenu> 
          <guimenuitem>Query Fragments</guimenuitem></menuchoice> menu
          entry will open a window with radio- and check-buttons which
          can be used to activate query language fragments for
          filtering the current query. This can be useful if you have
          frequent reusable selectors, for example, filtering on
          alternate directories, or searching just one category of
          files, not covered by the standard category
          selectors.</para>

      <para>The contents of the window are entirely customizable, and
      defined by the contents of the <filename>fragbuts.xml</filename>
      file inside the configuration directory. The sample file
      distributed with &RCL; (which you should be able to find under
      <filename>/usr/share/recoll/examples/fragbuts.xml</filename>),
      contains an example which filters the results from the WEB
      history.</para>

      <para>Here follows an example:
<programlisting>
&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;

&lt;fragbuts version=&quot;1.0&quot;&gt;

  &lt;radiobuttons&gt;

    &lt;fragbut&gt;
      &lt;label&gt;Include Web Results&lt;/label&gt;
      &lt;frag&gt;&lt;/frag&gt;
    &lt;/fragbut&gt;

    &lt;fragbut&gt;
      &lt;label&gt;Exclude Web Results&lt;/label&gt;
      &lt;frag&gt;-rclbes:BGL&lt;/frag&gt;
    &lt;/fragbut&gt;

    &lt;fragbut&gt;
      &lt;label&gt;Only Web Results&lt;/label&gt;
      &lt;frag&gt;rclbes:BGL&lt;/frag&gt;
    &lt;/fragbut&gt;

  &lt;/radiobuttons&gt;

  &lt;buttons&gt;

    &lt;fragbut&gt;
      &lt;label&gt;Year 2010&lt;/label&gt;
      &lt;frag&gt;date:2010-01-01/2010-12-31&lt;/frag&gt;
    &lt;/fragbut&gt;

    &lt;fragbut&gt;
      &lt;label&gt;My Great Directory Only&lt;/label&gt;
      &lt;frag&gt;dir:/my/great/directory&lt;/frag&gt;
    &lt;/fragbut&gt;

  &lt;/buttons&gt;
&lt;/fragbuts&gt;
</programlisting>
      </para>
      
      <para>Each <literal>radiobuttons</literal> or
      <literal>buttons</literal> section defines a line of
      checkbuttons or radiobuttons inside the window. Any number of
      buttons can be selected, but the radiobuttons in a line are
      exclusive.</para>
      
      <para>Each <literal>fragbut</literal> section defines the label
      for a button, and the Query Language fragment which will be
      added (as an AND filter) before performing the query if the
      button is active.</para>

      <para>This feature is new in &RCL; 1.20, and will probably be
      refined depending on user feedback.</para>

    </sect2>


    <sect2 id="RCL.SEARCH.GUI.COMPLEX">
      <title>Complex/advanced search</title>

      <para>The advanced search dialog helps you build more complex queries
        without memorizing the search language constructs. It can be opened
        through the <guilabel>Tools</guilabel> menu or through the main
        toolbar.</para>

        <para>&RCL; keeps a history of searches. See 
        <link linkend="RCL.SEARCH.GUI.COMPLEX.HISTORY">
        Advanced search history</link>.</para> 

      <para>The dialog has two tabs:</para> 

      <orderedlist>

      <listitem><para>The first tab lets you specify terms to search
          for, and permits specifying multiple clauses which are combined
          to build the search.</para>
         </listitem> 

      <listitem><para>The second tab lets filter the results according
          to file size, date of modification, MIME type, or
          location.</para>
         </listitem>
     
      </orderedlist>

      <para>Click on the <guilabel>Start Search</guilabel> button in
        the advanced search dialog, or type <keycap>Enter</keycap> in
        any text field to start the search. The button in
        the main window always performs a simple search.</para>

      <para>Click on the <literal>Show query details</literal> link at
        the top of the result page to see the query expansion.</para>

      <sect3 id="RCL.SEARCH.GUI.COMPLEX.TERMS">
        <title>Avanced search: the "find" tab</title>

        <para>This part of the dialog lets you constructc a query by
          combining multiple clauses of different types.  Each entry
          field is configurable for the following modes:</para>

        <itemizedlist>
          <listitem><para>All terms.</para>
          </listitem>
          <listitem><para>Any term.</para>
          </listitem>
          <listitem><para>None of the terms.</para>
          </listitem>
          <listitem><para>Phrase (exact terms in order within an
          adjustable window).</para>
          </listitem>
          <listitem><para>Proximity (terms in any order within an
          adjustable window).</para>
          </listitem>
          <listitem><para>Filename search.</para>
          </listitem>
        </itemizedlist>

        <para>Additional entry fields can be created by clicking the
          <guilabel>Add clause</guilabel> button.</para>

        <para>When searching, the non-empty clauses will be
          combined either with an AND or an OR conjunction, depending on
          the choice made on the left (<guilabel>All clauses</guilabel> or
          <guilabel>Any clause</guilabel>).</para>

        <para>Entries of all types except "Phrase" and "Near" accept
          a mix of single words and phrases enclosed in double quotes. 
          Stemming and wildcard expansion will be performed as for simple
          search. </para>

      <formalpara><title>Phrases and Proximity searches</title>
      <para>These two clauses work in similar ways, with the
      difference that proximity searches do not impose an order on the
      words. In both cases, an adjustable number (slack) of non-matched words
      may be accepted between the searched ones (use the counter on
      the left to adjust this count). For phrases, the default count
      is zero (exact match). For proximity it is ten (meaning that two search
      terms, would be matched if found within a window of twelve
      words). Examples: a phrase search for <literal>quick
      fox</literal> with a slack of 0 will match <literal>quick
      fox</literal> but not <literal>quick brown fox</literal>. With
      a slack of 1 it will match the latter, but not <literal>fox
      quick</literal>. A proximity search for <literal>quick
      fox</literal> with the default slack will match the
      latter, and also <literal>a fox is a cunning and quick
      animal</literal>.</para> 
      </formalpara>

      </sect3>

      <sect3 id="RCL.SEARCH.GUI.COMPLEX.FILTER">
      <title>Avanced search: the "filter" tab</title>

      <para>This part of the dialog has several sections which allow
      filtering the results of a search according to a number of
      criteria</para>

      <itemizedlist>

      <listitem>
      <para>The first section allows filtering by dates of last
      modification. You can specify both a minimum and a maximum date. The
      initial values are set according to the oldest and newest documents
      found in the index.</para>
      </listitem>

      <listitem>
      <para>The next section allows filtering the results by
            file size. There are two entries for minimum and maximum
            size. Enter decimal numbers. You can use suffix multipliers:
            <literal>k/K</literal>, <literal>m/M</literal>,
            <literal>g/G</literal>, <literal>t/T</literal> for 1E3, 1E6,
            1E9, 1E12 respectively.</para>
      </listitem>

      <listitem>   
      <para>The next section allows filtering the results by their MIME
            types, or MIME categories (ie: media/text/message/etc.).</para>
          <para>You can transfer the types between two boxes, to define
            which will be included or excluded by the search.</para>
          <para>The state of the file type selection can be saved as
            the default (the file type filter will not be activated at
            program start-up, but the lists will be in the restored
            state).</para> 
      </listitem>

      <listitem>
          <para>The bottom section allows restricting the search results to a
            sub-tree of the indexed area. You can use the
            <guilabel>Invert</guilabel> checkbox to search for files not in
            the sub-tree instead. If you use directory filtering often and on
            big subsets of the file system, you may think of setting up
            multiple indexes instead, as the performance may be
            better.</para>
          <para>You can use relative/partial paths for filtering. Ie,
          entering <literal>dirA/dirB</literal> would match either
          <filename>/dir1/dirA/dirB/myfile1</filename> or
          <filename>/dir2/dirA/dirB/someother/myfile2</filename>.</para> 
      </listitem>

      </itemizedlist>

     </sect3>

      <sect3 id="RCL.SEARCH.GUI.COMPLEX.HISTORY">
        <title>Avanced search history</title>

        <para>The advanced search tool memorizes the last 100 searches
          performed. You can walk the saved searches by using the up and
          down arrow keys while the keyboard focus belongs to the advanced
          search dialog.</para>

        <para>The complex search history can be erased, along with the
          one for simple search, by selecting the <menuchoice>
	    <guimenu>File</guimenu>
	    <guimenuitem>Erase Search History</guimenuitem>
          </menuchoice> menu entry.</para>

      </sect3>

    </sect2>

    <sect2 id="RCL.SEARCH.GUI.TERMEXPLORER">
      <title>The term explorer tool</title>

      <para>&RCL; automatically manages the expansion of search terms
      to their derivatives (ie: plural/singular, verb
      inflections). But there are other cases where the exact search
      term is not known. For example, you may not remember the exact
      spelling, or only know the beginning of the name.</para>

      <para>The search will only propose replacement terms with
      spelling variations when no matching document were found. In some
      cases, both proper spellings and mispellings are present in the
      index, and it may be interesting to look for them explicitely.</para>

      <para>The term explorer tool (started from the toolbar icon or
      from the <guilabel>Term explorer</guilabel> entry of the
      <guilabel>Tools</guilabel> menu) can be used to search the full index
      terms list. It has three modes of operations:</para>
        <variablelist>

          <varlistentry>
            <term>Wildcard</term>
            <listitem><para>In this mode of operation, you can enter a
            search string with shell-like wildcards (*, ?, []). ie:
            <replaceable>xapi*</replaceable> would display all index terms
            beginning with <replaceable>xapi</replaceable>. (More
            about wildcards <link
            linkend="RCL.SEARCH.WILDCARDS">here</link>).</para></listitem> 
          </varlistentry>

          <varlistentry>
          <term>Regular expression</term>
          <listitem><para>This mode will accept a regular expression
            as input. Example:
            <replaceable>word[0-9]+</replaceable>. The expression is
            implicitely anchored at the beginning. Ie:
            <replaceable>press</replaceable> will match
            <replaceable>pression</replaceable> but not
            <replaceable>expression</replaceable>. You can use
            <replaceable>.*press</replaceable> to match the latter,
            but be aware that this will cause a full index term list
            scan, which can be quite long.</para>
          </listitem>
          </varlistentry>
          <varlistentry>

          <term>Stem expansion</term>
          <listitem><para>This mode will perform the usual stem expansion
          normally done as part user input processing. As such it is
          probably mostly useful to demonstrate the process.
          </para></listitem>
          </varlistentry>

          <varlistentry>
            <term>Spelling/Phonetic</term> <listitem><para>In this
            mode, you enter the term as you think it is spelled, and
            &RCL; will do its best to find index terms that sound like
            your entry. This mode uses the
            <application>Aspell</application> spelling application,
            which must be installed on your system for things to work
            (if your documents contain non-ascii characters, &RCL;
            needs an aspell version newer than 0.60 for UTF-8
            support). The language which is used to build the
            dictionary out of the index terms (which is done at the
            end of an indexing pass) is the one defined by your NLS
            environment. Weird things will probably happen if
            languages are mixed up.</para></listitem>
          </varlistentry>
      </variablelist>

      <para>Note that in cases where &RCL; does not know the beginning
      of the string to search for (ie a wildcard expression like
      <replaceable>*coll</replaceable>), the expansion can take quite
      a long time because the full index term list will have to be
      processed. The expansion is currently limited at 10000 results for
      wildcards and regular expressions. It is possible to change the
      limit in the configuration file.</para>
      
      <para>Double-clicking on a term in the result list will insert
      it into the simple search entry field. You can also cut/paste
      between the result list and any entry field (the end of lines
      will be taken care of).</para>

    </sect2>

    <sect2 id="RCL.SEARCH.GUI.MULTIDB">
      <title>Multiple indexes</title>

      <para>See the <link linkend="RCL.INDEXING.CONFIG.MULTIPLE">section
	  describing the use of multiple indexes</link> for
	generalities. Only the aspects concerning
	the <command>recoll</command> GUI are described here.</para>

      <para>A <command>recoll</command> program instance is always
	associated with a specific index, which is the one to be updated
	when requested from the <guimenu>File</guimenu> menu, but it can
	use any number of &RCL; indexes for searching. The external
	indexes can be selected through the <guilabel>external
	  indexes</guilabel> tab in the preferences dialog.</para>

      <para>Index selection is performed in two phases. A set of all
	usable indexes must first be defined, and then the subset of
	indexes to be used for searching. These parameters
	are retained across program executions (there are kept
	separately for each &RCL; configuration). The set of all indexes
	is usually quite stable, while the active ones might typically
	be adjusted quite frequently.</para>

      <para>The main index (defined by
	<envar>RECOLL_CONFDIR</envar>) is always active. If this is
	undesirable, you can set up your base configuration to index
	an empty directory.</para>

      <para>When adding a new index to the set, you can select either
        a &RCL; configuration directory, or directly a &XAP; index
        directory. In the first case, the &XAP; index directory will
        be obtained from the selected configuration.</para>

      <para>As building the set of all indexes can be a little tedious
	when done through the user interface, you can use the
	<envar>RECOLL_EXTRA_DBS</envar> environment
	variable to provide an initial set. This might typically be
	set up by a system administrator so that every user does not
	have to do it. The variable should define a colon-separated list
	of index  directories, ie: 
      </para>
      <screen>export RECOLL_EXTRA_DBS=/some/place/xapiandb:/some/other/db</screen> 

      <para>Another environment variable, 
        <envar>RECOLL_ACTIVE_EXTRA_DBS</envar> allows adding to the active
        list of indexes. This variable was suggested and implemented by a
        &RCL; user. It is mostly useful if you use scripts to mount
        external volumes with &RCL; indexes. By using
        <envar>RECOLL_EXTRA_DBS</envar> and
        <envar>RECOLL_ACTIVE_EXTRA_DBS</envar>, you can add and activate
        the index for the mounted volume when starting
        <command>recoll</command>.
      </para>
      
      <para><envar>RECOLL_ACTIVE_EXTRA_DBS</envar> is available for
        &RCL; versions 1.17.2 and later. A change was made in the same
        update so that <command>recoll</command> will
        automatically deactivate unreachable indexes when starting
        up.</para>

    </sect2>

    <sect2 id="RCL.SEARCH.GUI.HISTORY">
      <title>Document history</title>

      <para>Documents that you actually view (with the internal preview
        or an external tool) are entered into the document history,
        which is remembered.</para> 
      <para>You can display the history list by using
        the <guilabel>Tools/</guilabel><guilabel>Doc History</guilabel> menu
        entry.</para> 
      <para>You can erase the document history by using the
      <guilabel>Erase document history</guilabel> entry in the
      <guimenu>File</guimenu> menu.</para>

    </sect2>

    <sect2 id="RCL.SEARCH.GUI.SORT">
      <title>Sorting search results and collapsing duplicates</title>

      <para>The documents in a result list are normally sorted in
        order of relevance. It is possible to specify a different sort
        order, either by using the vertical arrows in the GUI toolbox to
        sort by date, or switching to the result table display and clicking
        on any header. The sort order chosen inside the result table
        remains active if you switch back to the result list, until you
        click one of the vertical arrows, until both are unchecked (you are
        back to sort by relevance).</para>

      <para>Sort parameters are remembered between program
        invocations, but result sorting is normally always inactive
        when the program starts. It is possible to keep the sorting
        activation state between program invocations by checking the
        <guilabel>Remember sort activation state</guilabel> option in
        the preferences.</para>

      <para>It is also possible to hide duplicate entries inside
        the result list (documents with the exact same contents as the
        displayed one). The test of identity is based on an MD5 hash
        of the document container, not only of the text contents (so
        that ie, a text document with an image added will not be a
        duplicate of the text only). Duplicates hiding is controlled
        by an entry in the <guilabel>GUI configuration</guilabel>
        dialog, and is off by default.</para>

      <para>As of release 1.19, when a result document does have
        undisplayed duplicates, a <literal>Dups</literal>
        link will be shown with the result list entry. Clicking the
        link will display the paths (URLs + ipaths) for the duplicate
        entries.</para>

    </sect2>

    <sect2 id="RCL.SEARCH.GUI.TIPS">
      <title>Search tips, shortcuts</title>

    <sect3 id="RCL.SEARCH.GUI.TIPS.TERMS">
      <title>Terms and search expansion</title>

      <formalpara><title>Term completion</title>
        <para>Typing <keycap>Esc</keycap> <keycap>Space</keycap> in
        the simple search entry field while entering a word will
        either complete the current word if its beginning matches a
        unique term in the index, or open a window to propose a list
        of completions.</para>
      </formalpara>

      <formalpara><title>Picking up new terms from result or preview 
                   text</title>
        <para>Double-clicking on a word in the result list or in a
        preview window will copy it to the simple search entry field.</para>
      </formalpara>

      <formalpara><title>Wildcards</title>
          <para>Wildcards can be used inside search terms in all forms
            of searches. <link linkend="RCL.SEARCH.WILDCARDS">
            More about wildcards</link>.
          </para>
      </formalpara>

      <formalpara><title>Automatic suffixes</title>
          <para>Words like <literal>odt</literal> or <literal>ods</literal>
            can be automatically turned into query language
            <literal>ext:xxx</literal> clauses. This can be enabled in the
            <guilabel>Search preferences</guilabel> panel in the GUI.
          </para>
      </formalpara>

      <formalpara><title>Disabling stem expansion</title>
      <para>Entering a capitalized word in any search field will prevent
        stem expansion (no search for
        <literal>gardening</literal> if you enter
        <literal>Garden</literal> instead of
        <literal>garden</literal>). This is the only case where
        character case should make a difference for a &RCL;
        search. You can also disable stem expansion or change the
        stemming language in the preferences.</para>
      </formalpara>

      <formalpara><title>Finding related documents</title>
        <para>Selecting the <guilabel>Find similar documents</guilabel> entry
        in the result list paragraph right-click menu will select a
        set of "interesting" terms from the current result, and insert
        them into the simple search entry field. You can then possibly
        edit the list and start a search to find documents which may
        be apparented to the current result.</para>
      </formalpara>

      <formalpara><title>File names</title>
        <para>File names are added as terms during indexing, and you can
        specify them as ordinary terms in normal search fields (&RCL; used
        to index all directories in the file path as terms. This has been
        abandoned as it did not seem really useful). Alternatively, you
        can use the specific file name search which will
        <emphasis>only</emphasis> look for file names, and may be
        faster than the generic search especially when using wildcards.</para>
      </formalpara>

      </sect3>


    <sect3 id="RCL.SEARCH.GUI.TIPS.PHRASES">
      <title>Working with phrases and proximity</title>

      <formalpara><title>Phrases and Proximity searches</title>
      <para>A phrase can be looked for by enclosing it in double
        quotes. Example: <literal>"user manual"</literal> will look
        only for occurrences of <literal>user</literal> immediately
        followed by <literal>manual</literal>. You can use the
        <guilabel>This phrase</guilabel> field of the advanced
        search dialog to the same effect. Phrases can be entered along
        simple terms in all simple or advanced search entry fields
        (except <guilabel>This exact phrase</guilabel>).</para>
      </formalpara>

      <formalpara><title>AutoPhrases</title>
      <para>This option can be set in the preferences dialog. If it is
        set, a phrase will be automatically built and added to simple
        searches when looking for <literal>Any terms</literal>. This
        will not change radically the results, but will give a relevance
        boost to the results where the search terms appear as a
        phrase. Ie: searching for <literal>virtual reality</literal>
        will still find all documents where either
        <literal>virtual</literal> or <literal>reality</literal> or 
        both appear, but those which contain <literal>virtual
          reality</literal> should appear sooner in the list.</para>
          </formalpara>

      <para>Phrase searches can strongly slow down a query if most of the
        terms in the phrase are common. This is why the
        <varname>autophrase</varname> option is off by default for &RCL;
        versions before 1.17. As of version 1.17,
        <varname>autophrase</varname> is on by default, but very common
        terms will be removed from the constructed phrase. The removal
        threshold can be adjusted from the search preferences.</para>

      <formalpara><title>Phrases and abbreviations</title> <para>As of
      &RCL; version 1.17, dotted abbreviations like
      <literal>I.B.M.</literal> are also automatically indexed as a word
      without the dots: <literal>IBM</literal>. Searching for the word
      inside a phrase (ie: <literal>"the IBM company"</literal>) will only
      match the dotted abrreviation if you increase the phrase slack (using the
      advanced search panel control, or the <literal>o</literal> query
      language modifier). Literal occurences of the word will be matched
      normally.</para></formalpara>


      </sect3>

    <sect3 id="RCL.SEARCH.GUI.TIPS.MISC">
      <title>Others</title>

      <formalpara><title>Using fields</title>
        <para>You can use the <link linkend="RCL.SEARCH.LANG">query
        language </link> and field specifications
        to only search certain parts of documents. This can be
        especially helpful with email, for example only searching
        emails from a specific originator:
        <literal>search tips from:helpfulgui</literal>
        </para>
      </formalpara>

      <formalpara><title>Ajusting the result table columns</title>
        <para>When displaying results in table mode, you can use a
        right click on the table headers to activate a pop-up menu
        which will let you adjust what columns are displayed. You can
        drag the column headers to adjust their order. You can click
        them to sort by the field displayed in the column.  You can
        also save the result list in CSV format.</para> 
      </formalpara>


      <formalpara><title>Changing the GUI geometry</title>
      <para>It is possible to configure the GUI in wide form
      factor by dragging the toolbars to one of the sides (their
      location is remembered between sessions), and moving the
      category filters to a menu (can be set in the 
	  <menuchoice>
	    <guimenu>Preferences</guimenu>
	    <guimenuitem>GUI configuration</guimenuitem>
	    <guimenuitem>User interface</guimenuitem>
          </menuchoice> panel).</para>
      </formalpara>

      <formalpara><title>Query explanation</title>
        <para>You can get an exact description of what the query
        looked for, including stem expansion, and Boolean operators
        used, by clicking on the result list header.</para>
      </formalpara>

      <formalpara><title>Advanced search history</title>
        <para>As of &RCL; 1.18, you can display any of the last 100 complex
          searches performed by using the up and down arrow keys while the
          advanced search panel is active.</para>
      </formalpara>
      
      <formalpara><title>Browsing the result list inside a preview 
                   window</title>
       <para>Entering <keycap>Shift-Down</keycap> or <keycap>Shift-Up</keycap>
       (<keycap>Shift</keycap> + an arrow key) in a preview window will
       display the next or the previous document from the result
       list. Any secondary search currently active will be executed on
       the new document.</para>
      </formalpara>

      <formalpara><title>Scrolling the result list from the keyboard</title>
       <para>You can use <keycap>PageUp</keycap> and <keycap>PageDown</keycap>
	 to scroll the result list, <keycap>Shift+Home</keycap> to go back
	 to the first page. These work even while the focus is in the
	 search entry.</para>
      </formalpara>
      
      <formalpara><title>Result table: moving the focus to the table</title>
      <para>You can use <keycap>Ctrl-r</keycap> to move the focus
      from the search entry to the table, and then use the arrow keys
      to change the current row. <keycap>Ctrl-Shift-s</keycap> returns to 
      the search.</para>
      </formalpara>

      <formalpara><title>Result table: open / preview</title>
      <para>With the focus in the result table, you can use
      <keycap>Ctrl-o</keycap> to open the document from the current
      row, <keycap>Ctrl-Shift-o</keycap> to open the document and close
      <command>recoll</command>, <keycap>Ctrl-d</keycap> to preview
      the document.</para>
      </formalpara>

      <formalpara><title>Editing a new search while the focus is not
          in the search entry</title>
       <para>You can use the <keycap>Ctrl-Shift-S</keycap> shortcut to
         return the cursor to the search entry (and select the current
         search text), while the focus is anywhere in the main
         window.</para>
      </formalpara>
      
      <formalpara><title>Forced opening of a preview window</title>
       <para>You can use <keycap>Shift</keycap>+Click on a result list
       <literal>Preview</literal> link to force the creation of a
       preview window instead of a new tab in the existing one.</para>
      </formalpara>

      <formalpara><title>Closing previews</title> 
       <para>Entering <keycap>Ctrl-W</keycap> in a tab will
        close it (and, for the last tab, close the preview
        window). Entering <keycap>Esc</keycap> will close the preview
        window and all its tabs.</para>
      </formalpara>

      <formalpara><title>Printing previews</title> 
       <para>Entering <keycap>Ctrl-P</keycap> in a preview window will print 
        the currently displayed text.</para>
      </formalpara>

      <formalpara><title>Quitting</title>
      <para>Entering <keycap>Ctrl-Q</keycap> almost anywhere will
        close the application.</para>
      </formalpara>
      </sect3>
    </sect2>

    <sect2 id="RCL.SEARCH.SAVING">
      <title>Saving and restoring queries (1.21 and later)</title>

      <para>Both simple and advanced query dialogs save recent
      history, but the amount is limited: old queries will eventually
      be forgotten. Also, important queries may be difficult to find
      among others. This is why both types of queries can also be
      explicitely saved to files, from the GUI menus:
	  <menuchoice>
	    <guimenu>File</guimenu>
	    <guimenuitem>Save last query / Load last query</guimenuitem>
          </menuchoice>
      </para>

      <para>The default location for saved queries is a subdirectory
      of the current configuration directory, but saved queries are
      ordinary files and can be written or moved anywhere.</para>

      <para>Some of the saved query parameters are part of the
      preferences (e.g. <literal>autophrase</literal> or the active
      external indexes), and may differ when the query is
      loaded from the time it was saved. In this case, &RCL; will warn
      of the differences, but will not change the user
      preferences.</para>

    </sect2>

    <sect2 id="RCL.SEARCH.GUI.CUSTOM">
      <title>Customizing the search interface</title>

      <para>You can customize some aspects of the search interface by using
      the <guimenu>GUI configuration</guimenu> entry in the
      <guimenu>Preferences</guimenu> menu.</para>

      <para>There are several tabs in the dialog, dealing with the
      interface itself, the parameters used for searching and
      returning results, and what indexes are searched.</para> 


      <formalpara id="RCL.SEARCH.GUI.CUSTOM.UI">
       <title>User interface parameters:</title>
        <para>
      <itemizedlist>

            <listitem><para><guilabel>Highlight color for query
            terms</guilabel>: Terms from the user query are highlighted in
            the result list samples and the preview window. The color can
            be chosen here. Any Qt color string should work (ie
            <literal>red</literal>, <literal>#ff0000</literal>). The
            default is <literal>blue</literal>.</para>
            </listitem>

            <listitem><para><guilabel>Style sheet</guilabel>:
                The name of a <application>Qt</application> style sheet
                text file which is applied to the whole Recoll application
                on startup. The default value is empty, but there is a
                skeleton style sheet (<filename>recoll.qss</filename>)
                inside the <filename>/usr/share/recoll/examples</filename>
                directory. Using a style sheet, you can change most
                <command>recoll</command> graphical parameters:
                colors, fonts, etc. See the sample file for a few
                simple examples.</para> 
	      <para>You should be aware that parameters (e.g.: the
                background color) set inside the &RCL; GUI style sheet
                will override global system preferences, with possible
                strange side effects: for example if you set the
                foreground to a light color and the background to a
                dark one in the desktop preferences, but only the
                background is set inside the &RCL; style sheet, and it
                is light too, then text will appear light-on-light
                inside the &RCL; GUI.</para>
            </listitem>

	    <listitem><para><guilabel>Maximum text size highlighted for
            preview</guilabel> Inserting highlights on search term inside
            the text before inserting it in the preview window involves
            quite a lot of processing, and can be disabled over the given
            text size to speed up loading.</para>
            </listitem>

	    <listitem><para><guilabel>Prefer HTML to plain text for
	    preview</guilabel> if set, Recoll will display HTML as such
	    inside the preview window. If this causes problems with the Qt
	    HTML display, you can uncheck it to display the plain text
	    version instead. </para>
	    </listitem>

	    <listitem><para><guilabel>Plain text to HTML line style</guilabel>:
                when displaying plain text inside the preview window, &RCL;
                tries to preserve some of the original text line breaks and
                indentation. It can either use PRE HTML tags, which will
                well preserve the indentation but will force horizontal
                scrolling for long lines, or use BR tags to break at the
                original line breaks, which will let the editor introduce
                other line breaks according to the window width, but will
                lose some of the original indentation. The third option has
                been available in recent releases and is probably now the best
                one: use PRE tags with line wrapping.</para>
             </listitem>

            <listitem><para><guilabel>Use desktop preferences to choose
            document editor</guilabel>: if this is checked, the
            <command>xdg-open</command> utility will be used to open files
            when you click the <guilabel>Open</guilabel> link in the result
            list, instead of the application defined in
            <filename>mimeview</filename>. <command>xdg-open</command> will
            in term use your desktop preferences to choose an appropriate
            application.</para>
           </listitem>

            <listitem><para><guilabel>Exceptions</guilabel>: when using the
            desktop preferences for opening documents, these are MIME types
            that will still be opened according to &RCL; preferences. This
            is useful for passing parameters like page numbers or search
            strings to applications that support them
            (e.g. <application>evince</application>). This cannot be done
            with <command>xdg-open</command> which only supports passing
            one parameter.</para>
           </listitem>

            <listitem><para><guilabel>Choose editor applications</guilabel>
            this will let you choose the command started by the
            <guilabel>Open</guilabel> links inside the result list, for
            specific document types.</para>
            </listitem>
	    
	    <listitem><para><guilabel>Display category filter as
	    toolbar...</guilabel> this will let you choose if the document
	    categories are displayed as a list or a set of buttons.</para>
	    </listitem>

            <listitem><para><guilabel>Auto-start simple search on white
            space entry</guilabel>: if this is checked, a search will be
            executed each time you enter a space in the simple search input
            field. This lets you look at the result list as you enter new
            terms. This is off by default, you may like it or not...</para>
            </listitem>

	    <listitem><para><guilabel>Start with advanced search dialog open
            </guilabel>: If you use this dialog frequently, checking
            the entries will get it to open when recoll starts.</para>
	    </listitem>
	    
	    <listitem><para><guilabel>Remember sort activation
	    state</guilabel> if set, Recoll will remember the sort tool
	    stat between invocations. It normally starts with sorting
	    disabled.</para>
	    </listitem>

	  </itemizedlist>
      </para>
      </formalpara>


      <formalpara id="RCL.SEARCH.GUI.CUSTOM.RL">
       <title>Result list parameters:</title>
        <para>
          <itemizedlist>
            
            <listitem><para><guilabel>Number of results in a result
                  page</guilabel></para>
            </listitem>

            <listitem><para><guilabel>Result list font</guilabel>: There is
            quite a lot of information shown in the result list, and you
            may want to customize the font and/or font size. The rest of
            the fonts used by &RCL; are determined by your generic Qt
            config (try the <command>qtconfig</command> command).</para>
            </listitem>

            <listitem id="RCL.SEARCH.GUI.CUSTOM.RESULTPARA">
            <para><guilabel>Edit result list paragraph format string</guilabel>:
            allows you to change the presentation of each result list
            entry. See the <link linkend="RCL.SEARCH.GUI.CUSTOM.RESLIST">
                result list customisation section</link>.</para>
            </listitem>

            <listitem id="RCL.SEARCH.GUI.CUSTOM.RESULTHEAD">
            <para><guilabel>Edit result page HTML header insert</guilabel>:
            allows you to define text inserted at the end of the result
            page HTML header.  
            More detail in the <link linkend="RCL.SEARCH.GUI.CUSTOM.RESLIST"> 
                result list customisation section.</link></para>
            </listitem>

            <listitem>
            <para><guilabel>Date format</guilabel>: allows specifying the
            format used for displaying dates inside the result list. This
            should be specified as an strftime() string (man strftime).</para>
            </listitem>

            <listitem id="RCL.SEARCH.GUI.CUSTOM.ABSSEP">
            <para><guilabel>Abstract snippet separator</guilabel>:
            for synthetic abstracts built from index data, which are
            usually made of several snippets from different parts of the
            document, this defines the snippet separator, an ellipsis by
            default. </para>
            </listitem>

           </itemizedlist></para>
      </formalpara>

      <formalpara id="RCL.SEARCH.GUI.CUSTOM.SEARCH">
	<title>Search parameters:</title>
        <para>
      <itemizedlist>

            <listitem><para><guilabel>Hide duplicate results</guilabel>:
            decides if result list entries are shown for identical
            documents found in different places.</para>
            </listitem>

	    <listitem><para><guilabel>Stemming language</guilabel>:
            stemming obviously depends on the document's language. This
            listbox will let you chose among the stemming databases which
            were built during indexing (this is set in the <link
            linkend="RCL.INSTALL.CONFIG.RECOLLCONF">main configuration
            file</link>), or later added with <command>recollindex
            -s</command> (See the recollindex manual). Stemming languages
            which are dynamically added will be deleted at the next
            indexing pass unless they are also added in the configuration
            file.</para>
            </listitem>

            <listitem><para><guilabel>Automatically add phrase to simple
            searches</guilabel>: a phrase will be automatically built and
            added to simple searches when looking for <literal>Any
            terms</literal>. This will give a relevance boost to the
            results where the search terms appear as a phrase (consecutive
            and in order).</para>
            </listitem>

            <listitem><para><guilabel>Autophrase term frequency threshold
            percentage</guilabel>: very frequent terms should not be included
            in automatic phrase searches for performance reasons. The
            parameter defines the cutoff percentage (percentage of the
            documents where the term appears).</para>
            </listitem>

            <listitem><para><guilabel>Replace abstracts from
            documents</guilabel>: this decides if we should synthesize and
            display an abstract in place of an explicit abstract found
            within the document itself.</para>
            </listitem>

            <listitem><para><guilabel>Dynamically build
            abstracts</guilabel>: this decides if &RCL; tries to build
            document abstracts (lists of <emphasis>snippets</emphasis>)
            when displaying the result list. Abstracts are constructed by
            taking context from the document information, around the search
            terms.</para>
            </listitem>

            <listitem><para><guilabel>Synthetic abstract size</guilabel>:
            adjust to taste...</para>
            </listitem>

            <listitem><para><guilabel>Synthetic abstract context
            words</guilabel>: how many words should be displayed around
            each term occurrence.</para>
            </listitem>

            <listitem><para><guilabel>Query language magic file name 
              suffixes</guilabel>: a list of words which automatically get
              turned into <literal>ext:xxx</literal> file name suffix clauses
              when starting a query language query (ie: <literal>doc xls
              xlsx...</literal>). This will save some typing for people who
              use file types a lot when querying.</para>
            </listitem>
      </itemizedlist>
       </para>
      </formalpara>

      <formalpara id="RCL.SEARCH.GUI.CUSTOM.EXTRADB">
        <title>External indexes:</title> 
      <para>This panel will let you browse for additional indexes
      that you may want to search. External indexes are designated by
      their database directory (ie:
      <filename>/home/someothergui/.recoll/xapiandb</filename>,
      <filename>/usr/local/recollglobal/xapiandb</filename>).</para>
        </formalpara>

      <para>Once entered, the indexes will appear in the
        <guilabel>External indexes</guilabel> list, and you can
        chose which ones you want to use at any moment by checking or
        unchecking their entries.</para> 

      <para>Your main database (the one the current configuration
      indexes to), is always implicitly active. If this is not
      desirable, you can set up your configuration so that it indexes,
      for example, an empty directory. An alternative indexer may also
      need to implement a way of purging the index from stale data,
      </para>

    <sect3 id="RCL.SEARCH.GUI.CUSTOM.RESLIST">
      <title>The result list format</title>

        <para>Newer versions of Recoll (from 1.17) normally use WebKit HTML
        widgets for the result list and the 
        <link linkend="RCL.SEARCH.GUI.RESULTLIST.MENU.SNIPPETS">
          snippets window</link> (this may be disabled at build time). 
          Total customisation is possible with full support for CSS and
          Javascript. Conversely, there are limits to what you can do with
          the older Qt QTextBrowser, but still, it is possible to decide
          what data each result will contain, and how it will be
          displayed.</para>

        <para>The result list presentation can be exhaustively customized
          by adjusting two elements:

          <itemizedlist>
            <listitem><para>The paragraph format</para></listitem>
            <listitem><para>HTML code inside the header section. For
            versions 1.21 and later, this is also used for the
            <link linkend="RCL.SEARCH.GUI.RESULTLIST.MENU.SNIPPETS">            
            snippets window</link> </para></listitem>
          </itemizedlist>
          The paragraph format and the header fragment can be edited
          from the <guilabel>Result list</guilabel> tab of the
          <guilabel>GUI configuration</guilabel>.
        </para>

        <para>The header fragment is used both for the result list and
        the snippets window. The snippets list is a table and has a
        <literal>snippets</literal> class attribute. Each paragraph in
        the result list is a table, with class
        <literal>respar</literal>, but this can be changed by editing
        the paragraph format.</para>

        <para>There are a few examples on the 
          <ulink url="http://www.recoll.org/custom.html">page about 
            customising the result list</ulink> on the &RCL; web site.</para>

        <sect4 id="RCL.SEARCH.GUI.CUSTOM.RESLIST.PARA">
          <title>The paragraph format</title>

        <para>This is an arbitrary HTML string where the following printf-like
          <literal>%</literal> substitutions will be performed:

        <itemizedlist>
          <listitem>
            <formalpara><title>%A</title><para>Abstract</para></formalpara>
          </listitem>
          <listitem><formalpara><title>%D</title><para>Date</para></formalpara>
          </listitem>
          <listitem><formalpara><title>%I</title><para>Icon image
            name. This is normally determined from the MIME type. The
            associations are defined inside the 
            <link linkend="RCL.INSTALL.CONFIG.MIMECONF">
              <filename>mimeconf</filename> configuration file</link>. 
            If a thumbnail for the file is found at
            the standard Freedesktop location, this will be displayed
            instead.</para></formalpara> 
          </listitem>
          <listitem><formalpara><title>%K</title><para>Keywords (if
          any)</para></formalpara> 
          </listitem>
          <listitem><formalpara><title>%L</title><para>Precooked Preview,
            Edit, and possibly Snippets links</para></formalpara> 
          </listitem>
          <listitem><formalpara><title>%M</title><para>MIME
                  type</para></formalpara> 
          </listitem>
          <listitem><formalpara><title>%N</title><para>result Number inside
            the result page</para></formalpara> 
          </listitem>
          <listitem><formalpara><title>%P</title><para>Parent folder
          Url. In the case of an embedded document, this is the parent folder
          for the top level container file.</para></formalpara>
          </listitem>
          <listitem><formalpara><title>%R</title><para>Relevance
            percentage</para></formalpara> 
          </listitem>
          <listitem><formalpara><title>%S</title><para>Size
          information</para></formalpara> 
          </listitem>
          <listitem><formalpara><title>%T</title><para>Title or Filename if
          not set.</para></formalpara> 
          </listitem>
          <listitem><formalpara><title>%t</title><para>Title or Filename if
          not set.</para></formalpara> 
          </listitem>
          <listitem><formalpara><title>%U</title><para>Url</para></formalpara>
          </listitem>
        </itemizedlist>

        The format of the Preview, Edit, and Snippets links is 
        <literal>&lt;a href="P%N"&gt;</literal>,
        <literal>&lt;a href="E%N"&gt;</literal>
        and 
        <literal>&lt;a href="A%N"&gt;</literal>
        where <replaceable>docnum</replaceable> (%N) expands to the document
        number inside the result page).</para>

        <para>A link target defined as <literal>"F%N"</literal> will open
        the document corresponding to the <literal>%P</literal> parent
        folder expansion, usually creating a file manager window on the
        folder where the container file resides. E.g.:
        <programlisting>&lt;a href="F%N"&gt;%P&lt;/a&gt;</programlisting>
        </para>

        <para>A link target defined as
        <literal>R%N|<replaceable>scriptname</replaceable></literal> will
        run the corresponding script on the result file (if the document is
        embedded, the script will be started on the top-level parent).
        See the <link linkend="RCL.SEARCH.GUI.RUNSCRIPT">section about
        defining scripts</link>.</para>

        <para>In addition to the predefined values above, all strings
        like <literal>%(fieldname)</literal> will be replaced by the
        value of the field named <literal>fieldname</literal> for this
        document. Only stored fields can be accessed in this way, the
        value of indexed but not stored fields is not known at this
        point in the search process
        (see <link linkend="RCL.PROGRAM.FIELDS">field
        configuration</link>). There are currently very few fields
        stored by default, apart from the values above
        (only <literal>author</literal>
        and <literal>filename</literal>), so this feature will need
        some custom local configuration to be useful. An example
        candidate would be the <literal>recipient</literal> field
        which is generated by the message input handlers.</para>

        <para>The default value for the paragraph format string is:
        <screen><![CDATA[
    "<table class=\"respar\">\n"
    "<tr>\n"
    "<td><a href='%U'><img src='%I' width='64'></a></td>\n"
    "<td>%L &nbsp;<i>%S</i> &nbsp;&nbsp;<b>%T</b><br>\n"
    "<span style='white-space:nowrap'><i>%M</i>&nbsp;%D</span>&nbsp;&nbsp;&nbsp; <i>%U</i>&nbsp;%i<br>\n"
    "%A %K</td>\n"
    "</tr></table>\n"
]]></screen>

        You may, for example, try the following for a more web-like
        experience:

        <screen><![CDATA[
<u><b><a href="P%N">%T</a></b></u><br>
%A<font color=#008000>%U - %S</font> - %L
]]></screen>

       Note that the P%N link in the above paragraph makes the title a
       preview link. Or the clean looking:

        <screen><![CDATA[
<img src="%I" align="left">%L <font color="#900000">%R</font>
&nbsp;&nbsp;<b>%T&</b><br>%S&nbsp;
<font color="#808080"><i>%U</i></font>
<table bgcolor="#e0e0e0">
<tr><td><div>%A</div></td></tr>
</table>%K
]]></screen>
        </para>

        <para>These samples, and some others are 
          <ulink url="http://www.recoll.org/custom.html">on the web
            site, with pictures to show how they look.</ulink></para>

          <para>It is also possible to 
          <link linkend="RCL.SEARCH.GUI.CUSTOM.ABSSEP">
             define the value of the snippet separator inside the abstract
             section</link>.</para>
       </sect4>
      </sect3>
    </sect2>

  </sect1> <!-- search GUI -->

  <sect1 id="RCL.SEARCH.KIO">
    <title>Searching with the KDE KIO slave</title>

    <sect2 id="RCL.SEARCH.KIO.INTRO">
      <title>What's this</title>

      <para>The &RCL; KIO slave allows performing a &RCL; search
      by entering an appropriate URL in a KDE open dialog, or with an
      HTML-based interface displayed in
      <command>Konqueror</command>.</para>  

      <para>The HTML-based interface is similar to the Qt-based
      interface, but slightly less powerful for now. Its advantage is
      that you can perform your search while staying fully within the
      KDE framework: drag and drop from the result list works normally
      and you have your normal choice of applications for opening
      files.</para>

      <para>The alternative interface uses a directory view of search
      results. Due to limitations in the current KIO slave interface,
      it is currently not obviously useful (to me).</para>

      <para>The interface is described in more detail inside a help
      file which you can access by entering
      <filename>recoll:/</filename> inside the
      <command>konqueror</command> URL line (this works only if the
      recoll KIO slave has been previously installed).</para>


      <para>The instructions for building this module are located in the
      source tree. See:
      <filename>kde/kio/recoll/00README.txt</filename>. Some Linux
      distributions do package the kio-recoll module, so check before
      diving into the build process, maybe it's already out there ready for
      one-click installation.</para>
    </sect2>


    <sect2 id="RCL.SEARCH.KIO.SEARCHABLEDOCS">
      <title>Searchable documents</title>

      <para>As a sample application, the &RCL; KIO slave could allow
      preparing a set of HTML documents (for example a manual) so that
      they become their own search interface inside
      <command>konqueror</command>.</para>

      <para>This can be done by either explicitly inserting
      <literal><![CDATA[<a href="recoll://...">]]></literal> links 
      around some document areas, or automatically by adding a
      very small <application>javascript</application> program to the
      documents, like the following example, which would initiate a search by
      double-clicking any term:</para>
 
     <programlisting>&lt;script language="JavaScript">
    function recollsearch() {
        var t = document.getSelection();
        window.location.href = 'recoll://search/query?qtp=a&amp;p=0&amp;q=' +
            encodeURIComponent(t);
    }
&lt;/script>
 ....
&lt;body ondblclick="recollsearch()">

</programlisting>
    </sect2>
    </sect1>


  <sect1 id="RCL.SEARCH.COMMANDLINE">
    <title>Searching on the command line</title>

    <para>There are several ways to obtain search results as a text
    stream, without a graphical interface:</para>
    <itemizedlist>
      <listitem><para>By passing option <option>-t</option> to the
      <command>recoll</command> program.</para>
      </listitem>
      <listitem><para>By using the <command>recollq</command> program.</para>
      </listitem>
      <listitem><para>By writing a custom
      <application>Python</application> program, using the 
      <link linkend="RCL.PROGRAM.API.PYTHON">Recoll Python API</link>.</para>
      </listitem>
    </itemizedlist>

    <para>The first two methods work in the same way and accept/need the same
    arguments (except for the additional <option>-t</option> to
    <command>recoll</command>). The query to be executed is specified
    as command line arguments.</para> 

    <para><command>recollq</command> is not built by default. You can
    use the <filename>Makefile</filename> in the
    <filename>query</filename> directory to build it. This is a very
    simple program, and if you can program a little c++, you may find it
    useful to taylor its output format to your needs.</para>

    <para><command>recollq</command> has a man page (not installed by
    default, look in the <filename>doc/man</filename> directory). The
    Usage string is as follows:</para>
<programlisting>
recollq: usage:
 -P: Show the date span for all the documents present in the index
 [-o|-a|-f] [-q] &lt;query string&gt;
 Runs a recoll query and displays result lines. 
  Default: will interpret the argument(s) as a xesam query string
    query may be like: 
    implicit AND, Exclusion, field spec:    t1 -t2 title:t3
    OR has priority: t1 OR t2 t3 OR t4 means (t1 OR t2) AND (t3 OR t4)
    Phrase: "t1 t2" (needs additional quoting on cmd line)
  -o Emulate the GUI simple search in ANY TERM mode
  -a Emulate the GUI simple search in ALL TERMS mode
  -f Emulate the GUI simple search in filename mode
  -q is just ignored (compatibility with the recoll GUI command line)
Common options:
    -c &lt;configdir&gt; : specify config directory, overriding $RECOLL_CONFDIR
    -d also dump file contents
    -n [first-]&lt;cnt&gt; define the result slice. The default value for [first]
       is 0. Without the option, the default max count is 2000.
       Use n=0 for no limit
    -b : basic. Just output urls, no mime types or titles
    -Q : no result lines, just the processed query and result count
    -m : dump the whole document meta[] array for each result
    -A : output the document abstracts
    -S fld : sort by field &lt;fld&gt;
    -s stemlang : set stemming language to use (must exist in index...)
       Use -s "" to turn off stem expansion
    -D : sort descending
    -i &lt;dbdir&gt; : additional index, several can be given
    -e use url encoding (%xx) for urls
    -F &lt;field name list&gt; : output exactly these fields for each result.
       The field values are encoded in base64, output in one line and 
       separated by one space character. This is the recommended format 
       for use by other programs. Use a normal query with option -m to 
       see the field names.
</programlisting>

    <para>Sample execution:</para>
<programlisting>recollq 'ilur -nautique mime:text/html'
Recoll query: ((((ilur:(wqf=11) OR ilurs) AND_NOT (nautique:(wqf=11)
  OR nautiques OR nautiqu OR nautiquement)) FILTER Ttext/html))
4 results
text/html       [file:///Users/uncrypted-dockes/projets/bateaux/ilur/comptes.html]      [comptes.html]  18593   bytes   
text/html       [file:///Users/uncrypted-dockes/projets/nautique/webnautique/articles/ilur1/index.html] [Constructio...
text/html       [file:///Users/uncrypted-dockes/projets/pagepers/index.html]    [psxtcl/writemime/recoll]...
text/html       [file:///Users/uncrypted-dockes/projets/bateaux/ilur/factEtCie/recu-chasse-maree....
</programlisting>
      </sect1>

  <sect1 id="RCL.SEARCH.PTRANS">
    <title>Path translations</title>
    
    <para>In some cases, the document paths stored inside the index do
      not match the actual ones, so that document
      previews and accesses will fail. This can occur in a number of
      circumstances:</para>
    <itemizedlist>
      <listitem><para>When using multiple indexes it is a relatively common
          occurrence that some will actually reside on a remote volume, for
          exemple mounted via NFS. In this case, the paths used to access
          the documents on the local machine are not necessarily the same
          than the ones used while indexing on the remote machine. For
          example, <filename>/home/me</filename> may have been used as
          a <literal>topdirs</literal> elements while indexing, but the
          directory might be mounted
          as <filename>/net/server/home/me</filename> on the local
          machine.</para></listitem>

      <listitem><para>The case may also occur with removable
          disks. It is perfectly possible to configure an index to
          live with the documents on the removable disk, but it may
          happen that the disk is not mounted at the same place so
          that the documents paths from the index are
          invalid.</para></listitem>
      
      <listitem><para>As a last exemple, one could imagine that a big
          directory has been moved, but that it is currently
          inconvenient to run the indexer.</para></listitem>
    </itemizedlist>

    <para>More generally, the path translation facility may be useful
      whenever the documents paths seen by the indexer are not the same
      as the ones which should be used at query time.</para>

    <para>&RCL; has a facility for rewriting access paths when
      extracting the data from the index. The translations can be
      defined for the main index and for any additional query
      index.</para>

    <para>In the above NFS example, &RCL; could be instructed to
      rewrite any <filename>file:///home/me</filename> URL from the
      index to <filename>file:///net/server/home/me</filename>,
      allowing accesses from the client.</para>

    <para>The translations are defined in the 
      <link linkend="RCL.INSTALL.CONFIG.PTRANS">
        <filename>ptrans</filename></link> configuration file, which
        can be edited by hand or from the GUI external indexes
      configuration dialog.</para>
  </sect1>



    <sect1 id="RCL.SEARCH.LANG">
      <title>The query language</title>

      <para>The query language processor is activated in the GUI
      simple search entry when the search mode selector is set to
      <guilabel>Query Language</guilabel>. It can also be used with the KIO
      slave or the command line search. It broadly has the same
      capabilities as the complex search interface in the
      GUI.</para>

      <para>The language is based on the (seemingly defunct) 
        <ulink url="http://www.xesam.org/main/XesamUserSearchLanguage95">
          Xesam</ulink> user search language specification.</para>

      <para>If the results of a query language search puzzle you and you
        doubt what has been actually searched for, you can use the GUI
        <literal>Show Query</literal> link at the top of the result list to
        check the exact query which was finally executed by Xapian.</para>

      <para>Here follows a sample request that we are going to
        explain:</para>

      <programlisting>
          author:"john doe" Beatles OR Lennon Live OR Unplugged -potatoes
      </programlisting>

      <para>This would search for all documents with 
      <replaceable>John Doe</replaceable>
      appearing as a phrase in the author field (exactly what this is
      would depend on the document type, ie: the
      <literal>From:</literal> header, for an email message),
      and containing either <replaceable>beatles</replaceable> or
      <replaceable>lennon</replaceable> and either
      <replaceable>live</replaceable> or
      <replaceable>unplugged</replaceable> but not
      <replaceable>potatoes</replaceable> (in any part of the document).</para>

      <para>An element is composed of an optional field specification,
      and a value, separated by a colon (the field separator is the last
      colon in the element). Examples:
      <replaceable>Eugenie</replaceable>,
      <replaceable>author:balzac</replaceable>,
      <replaceable>dc:title:grandet</replaceable> 
      <replaceable>dc:title:"eugenie grandet"</replaceable> 
      </para>

      <para>The colon, if present, means "contains". Xesam defines other
      relations, which are mostly unsupported for now (except in special
      cases, described further down).</para>

      <para>All elements in the search entry are normally combined
      with an implicit AND. It is possible to specify that elements be
      OR'ed instead, as in <replaceable>Beatles</replaceable>
      <literal>OR</literal> <replaceable>Lennon</replaceable>. The
      <literal>OR</literal> must be entered literally (capitals), and
      it has priority over the AND associations:
      <replaceable>word1</replaceable>
      <replaceable>word2</replaceable> <literal>OR</literal>
      <replaceable>word3</replaceable> 
      means 
      <replaceable>word1</replaceable> AND 
      (<replaceable>word2</replaceable> <literal>OR</literal>
      <replaceable>word3</replaceable>)
      not 
      (<replaceable>word1</replaceable> AND
      <replaceable>word2</replaceable>) <literal>OR</literal>
      <replaceable>word3</replaceable>. Explicit
      parenthesis are <emphasis>not</emphasis> supported.</para>

      <para>As of &RCL; 1.21, you can use parentheses to group
      elements, which will sometimes make things clearer, and may
      allow expressing combinations which would have been difficult
      otherwise.</para>

      <para>An element preceded by a <literal>-</literal> specifies a
      term that should <emphasis>not</emphasis> appear.</para>

      <para>As usual, words inside quotes define a phrase
      (the order of words is significant), so that
      <replaceable>title:"prejudice pride"</replaceable> is not the same as
      <replaceable>title:prejudice title:pride</replaceable>, and is
      unlikely to find a result.</para> 

      <para>Words inside phrases and capitalized words are not
        stem-expanded. Wildcards may be used anywhere inside a term.
        Specifying a wild-card on the left of a term can produce a very
        slow search (or even an incorrect one if the expansion is
        truncated because of excessive size). Also see 
        <link linkend="RCL.SEARCH.WILDCARDS">
          More about wildcards</link>.</para>

      <para>To save you some typing, recent &RCL; versions (1.20 and later)
      interpret a comma-separated list of terms as an AND list inside the
      field. Use slash characters ('/') for an OR list. No white space
      is allowed. So
      <programlisting>author:john,lennon</programlisting> will search for
      documents with <literal>john</literal> and <literal>lennon</literal>
      inside the <literal>author</literal> field (in any order), and
      <programlisting>author:john/ringo</programlisting> would search for
      <literal>john</literal> or <literal>ringo</literal>.</para>

      <para>Modifiers can be set on a double-quote value, for example to specify
        a proximity search (unordered). See 
        <link linkend="RCL.SEARCH.LANG.MODIFIERS">the modifier
          section</link>. No space must separate the final
          double-quote and the modifiers value, e.g. <replaceable>"two
          one"po10</replaceable></para>

      <para>&RCL; currently manages the following default fields:</para>

      <itemizedlist>

        <listitem><para><literal>title</literal>,
            <literal>subject</literal> or <literal>caption</literal> are
            synonyms which specify data to be searched for in the
            document title or subject.</para>
           </listitem>

        <listitem><para><literal>author</literal> or
            <literal>from</literal> for searching the documents
            originators.</para>
           </listitem>

        <listitem><para><literal>recipient</literal> or
            <literal>to</literal> for searching the documents
            recipients.</para>
           </listitem>

        <listitem><para><literal>keyword</literal> for searching the
            document-specified keywords (few documents actually have
            any).</para>
           </listitem>

         <listitem><para><literal>filename</literal> for the document's
            file name. This is not necessarily set for all documents:
           internal documents contained inside a compound one (for example
           an EPUB section) do not inherit the container file name any more,
           this was replaced by an explicit field (see next). Sub-documents
           can still have a specific <literal>filename</literal>, if it is
           implied by the document format, for example the attachment file
           name for an email attachment.</para></listitem> 

         <listitem><para><literal>containerfilename</literal>. This is
           set for all documents, both top-level and contained
           sub-documents, and is always the name of the filesystem directory
           entry which contains the data. The terms from this field can
           only be matched by an explicit field specification (as opposed
           to terms from <literal>filename</literal> which are also indexed
           as general document content). This avoids getting matches for
           all the sub-documents when searching for the container file
           name.</para></listitem> 
           
        <listitem><para><literal>ext</literal> specifies the file
            name extension (Ex: <literal>ext:html</literal>)</para>
           </listitem>

      </itemizedlist>

      <para>&RCL; 1.20 and later have a way to specify aliases for the
      field names, which will save typing, for example by aliasing
      <literal>filename</literal> to <replaceable>fn</replaceable> or
      <literal>containerfilename</literal> to
      <replaceable>cfn</replaceable>. See the <link
      linkend="RCL.INSTALL.CONFIG.FIELDS">section about the
      <filename>fields</filename> file</link></para> 

      <para>The field syntax also supports a few field-like, but
        special, criteria:</para>

      <itemizedlist>

        <listitem><para><literal>dir</literal> for filtering the
            results on file location
            (Ex: <literal>dir:/home/me/somedir</literal>). 
            <literal>-dir</literal>
            also works to find results not in the specified directory
            (release >= 1.15.8). Tilde expansion will be performed as
            usual (except for a bug in versions 1.19 to
            1.19.11p1). Wildcards will be expanded, but
            please <link linkend="RCL.SEARCH.WILDCARDS.PATH"> have a
            look</link> at an important limitation of wildcards in
            path filters.</para>

           <para>Relative paths also make sense, for example, 
            <literal>dir:share/doc</literal> would match either
            <filename>/usr/share/doc</filename> or
            <filename>/usr/local/share/doc</filename> </para>

          <para>Several <literal>dir</literal> clauses can be specified,
          both positive and negative. For example the following makes sense:
            <programlisting>
dir:recoll dir:src -dir:utils -dir:common
            </programlisting> This would select results which have both
            <filename>recoll</filename> and <filename>src</filename> in the
            path (in any order), and which have not either
            <filename>utils</filename> or
            <filename>common</filename>.</para>

          <para>You can also use <literal>OR</literal> conjunctions
            with <literal>dir:</literal> clauses.</para>

          <para>A special aspect of <literal>dir</literal> clauses is
            that the values in the index are not transcoded to UTF-8, and
            never lower-cased or unaccented, but stored as binary. This means
            that you need to enter the values in the exact lower or upper
            case, and that searches for names with diacritics may sometimes
            be impossible because of character set conversion
            issues. Non-ASCII UNIX file paths are an unending source of
            trouble and are best avoided.</para> 

          <para>You need to use double-quotes around the path value if it
            contains space characters.</para> 

           </listitem>

        <listitem><para><literal>size</literal> for filtering the
            results on file size. Example: 
            <literal>size&lt;10000</literal>. You can use
            <literal>&lt;</literal>, <literal>&gt;</literal> or
            <literal>=</literal> as operators. You can specify a range like the
            following: <literal>size>100 size&lt;1000</literal>. The usual
            <literal>k/K, m/M, g/G, t/T</literal> can be used as (decimal)
            multipliers. Ex: <literal>size&gt;1k</literal> to search for files
            bigger than 1000 bytes.</para>
           </listitem>

        <listitem><para><literal>date</literal> for searching or filtering
            on dates. The syntax for the argument is based on the ISO8601
            standard for dates and time intervals. Only dates are supported, no
            times. The general syntax is 2 elements separated by a
            <literal>/</literal> character. Each element can be a date or a
            period of time. Periods are specified as 
            <literal>P</literal><replaceable>n</replaceable><literal>Y</literal><replaceable>n</replaceable><literal>M</literal><replaceable>n</replaceable><literal>D</literal>. 
            The <replaceable>n</replaceable> numbers are the respective numbers
            of years, months or days, any of which may be missing. Dates are
            specified as  
            <replaceable>YYYY</replaceable>-<replaceable>MM</replaceable>-<replaceable>DD</replaceable>. 
            The days and months parts may be missing. If the
            <literal>/</literal> is present but an element is missing, the
            missing element is interpreted as the lowest or highest date in the
            index. Examples:</para>

	  <itemizedlist>
	    <listitem><para><literal>2001-03-01/2002-05-01</literal> the
	        basic syntax for an interval of dates.</para>
	       </listitem>
	    <listitem><para><literal>2001-03-01/P1Y2M</literal> the
	        same specified with a period.</para>
	       </listitem>
	    <listitem><para><literal>2001/</literal> from the beginning of
	        2001 to the latest date in the index.</para>
	       </listitem>
	    <listitem><para><literal>2001</literal> the whole year of
	        2001</para></listitem>
	    <listitem><para><literal>P2D/</literal> means 2 days ago up to
	        now if there are no documents with dates in the future.</para>
	       </listitem>
	    <listitem><para><literal>/2003</literal> all documents from
	        2003 or older.</para>
	       </listitem>
	     </itemizedlist>
	  <para>Periods can also be specified with small letters (ie:
	    p2y).</para> 
           </listitem>

        <listitem><para><literal>mime</literal> or
            <literal>format</literal> for specifying the
            MIME type. This one is quite special because you can specify
            several values which will be OR'ed (the normal default for the
            language is AND). Ex: <literal>mime:text/plain
              mime:text/html</literal>. Specifying an explicit boolean
            operator before a
            <literal>mime</literal> specification is not supported and
            will produce strange results. You can filter out certain types
            by using negation (<literal>-mime:some/type</literal>), and you can
            use wildcards in the value (<literal>mime:text/*</literal>).
            Note that <literal>mime</literal> is
            the ONLY field with an OR default. You do need to use
            <literal>OR</literal> with <literal>ext</literal> terms for
            example.</para> 
           </listitem>

        <listitem><para><literal>type</literal> or
            <literal>rclcat</literal> for specifying the category (as in
            text/media/presentation/etc.). The classification of MIME
            types in categories is defined in the &RCL; configuration
            (<filename>mimeconf</filename>), and can be modified or
            extended. The default category names are those which permit
            filtering results in the main GUI screen. Categories are OR'ed
            like MIME types above. This can't be negated with
            <literal>-</literal> either.</para>
           </listitem>

      </itemizedlist>

      <para>The document input handlers used while indexing have the
        possibility to create other fields with arbitrary names, and
        aliases may be defined in the configuration, so that the exact
        field search possibilities may be different for you if someone
        took care of the customisation.</para>

      <sect2 id="RCL.SEARCH.LANG.MODIFIERS">
        <title>Modifiers</title>

        <para>Some characters are recognized as search modifiers when found
          immediately after the closing double quote of a phrase, as in
          <literal>"some term"modifierchars</literal>. The actual "phrase"
          can be a single term of course. Supported modifiers:

        <itemizedlist>
            <listitem><para><literal>l</literal> can be used to turn off
            stemming (mostly makes sense with <literal>p</literal> because
            stemming is off by default for phrases).</para>
            </listitem>

            <listitem><para><literal>o</literal> can be used to specify a
            "slack" for phrase and proximity searches: the number of
            additional terms that may be found between the specified
            ones. If <literal>o</literal> is followed by an integer number,
            this is the slack, else the default is 10.</para>
            </listitem>

            <listitem><para><literal>p</literal> can be used to turn the
            default phrase search into a proximity one
            (unordered). Example:<literal>"order any in"p</literal></para>
            </listitem>

            <listitem><para><literal>C</literal> will turn on case
            sensitivity (if the index supports it).</para></listitem>

            <listitem><para><literal>D</literal> will turn on diacritics
                sensitivity (if the index supports it).</para></listitem>

            <listitem><para>A weight can be specified for a query element
            by specifying a decimal value at the start of the
            modifiers. Example: <literal>"Important"2.5</literal>.</para>
            </listitem>
          </itemizedlist>
      </para>


     </sect2> <!-- search modifiers -->

    </sect1> <!-- rcl.search.lang -->
      

    <sect1 id="RCL.SEARCH.CASEDIAC">
      <title>Search case and diacritics sensitivity</title>

      <para>For &RCL; versions 1.18 and later, and <emphasis>when working
          with a raw index</emphasis> (not the default), searches can be
          made sensitive
        to character case and diacritics. How this happens is controlled by
        configuration variables and what search data is entered.</para>

      <para>The general default is that searches are insensitive to case
      and diacritics. An entry of <literal>resume</literal> will match any
      of <literal>Resume</literal>, <literal>RESUME</literal>,
      <literal>résumé</literal>, <literal>Résumé</literal> etc.</para>

      <para>Two configuration variables can automate switching on
        sensitivity:</para> 

      <variablelist>

        <varlistentry>
          <term>autodiacsens</term><listitem><para>If this is set, search
              sensitivity to diacritics will be turned on as soon as an
              accented character exists in a search term. When the variable
              is set to true, <literal>resume</literal> will start a
              diacritics-unsensitive search, but <literal>résumé</literal>
              will be matched exactly. The default value is
              <emphasis>false</emphasis>.</para></listitem>
        </varlistentry>

        <varlistentry>
          <term>autocasesens</term><listitem><para>If this is set, search
              sensitivity to character case will be turned on as soon as an
              upper-case character exists in a search term <emphasis>except
              for the first one</emphasis>. When the variable is set to
              true, <literal>us</literal> or <literal>Us</literal> will
              start a diacritics-unsensitive search, but
              <literal>US</literal> will be matched exactly. The default
              value is <emphasis>true</emphasis> (contrary to
              <literal>autodiacsens</literal>).</para></listitem>
        </varlistentry>

      </variablelist>
      
      <para>As in the past, capitalizing the first letter of a word will
        turn off its stem expansion and have no effect on
        case-sensitivity.</para>

      <para>You can also explicitely activate case and diacritics
      sensitivity by using modifiers with the query
      language. <literal>C</literal> will make the term case-sensitive, and
      <literal>D</literal> will make it
      diacritics-sensitive. Examples:</para>
      <programlisting>
        "us"C
   </programlisting>

      <para>will search for the term <literal>us</literal> exactly
      (<literal>Us</literal> will not be a match).</para>

      <programlisting>
        "resume"D
      </programlisting>
      <para>will search for the term <literal>resume</literal> exactly
      (<literal>résumé</literal> will not be a match).</para>


      <para>When either case or diacritics sensitivity is activated, stem
        expansion is turned off. Having both does not make much sense.</para>

   </sect1>

    <sect1 id="RCL.SEARCH.ANCHORWILD">
      <title>Anchored searches and wildcards</title>

      <para>Some special characters are interpreted by &RCL; in search
      strings to expand or specialize the search. Wildcards expand a root
      term in controlled ways. Anchor characters can restrict a search to
      succeed only if the match is found at or near the beginning of the
      document or one of its fields.</para>

    <sect2 id="RCL.SEARCH.WILDCARDS">
      <title>More about wildcards</title>

      <para>All words entered in &RCL; search fields will be processed
      for wildcard expansion before the request is finally
      executed.</para>

      <para>The wildcard characters are:</para>

      <itemizedlist>
       <listitem><para><literal>*</literal> which matches 0 or more 
        characters.</para>
        </listitem>
        <listitem><para><literal>?</literal> which matches
           a single character.</para>
        </listitem>
        <listitem><para><literal>[]</literal> which allow
         defining sets of characters to be matched (ex:
         <literal>[</literal><userinput>abc</userinput><literal>]</literal> 
          matches a single character which may be 'a' or 'b' or 'c',
         <literal>[</literal><userinput>0-9</userinput><literal>]</literal>
         matches any number.</para>
        </listitem>
      </itemizedlist>

      <para>You should be aware of a few things when using
        wildcards.</para>

      <itemizedlist>
        <listitem><para>Using a wildcard character at the beginning of
            a word can make for a slow search because &RCL; will have to
            scan the whole index term list to find the
            matches. However, this is much less a problem for field
            searches, and queries
            like <replaceable>author:*@domain.com</replaceable> can
            sometimes be very useful.</para></listitem>

        <listitem><para>For &RCL; version 18 only, when working with a
            raw index (preserving character case and diacritics), the
            literal part of a wildcard expression will be matched
            exactly for case and diacritics. This is not true any
            more for versions 19 and later.</para></listitem>

        <listitem><para>Using a <literal>*</literal> at the end of a
            word can produce more matches than you would think, and
            strange search results. You can use the 
            <link linkend="RCL.SEARCH.GUI.TERMEXPLORER">term 
              explorer</link> tool to check what completions exist for
            a given term. You can also see exactly what search was
            performed by clicking on the link at the top of the result
            list. In general, for natural language terms, stem
            expansion will produce better results than an
            ending <literal>*</literal> (stem expansion is turned off
            when any wildcard character appears in the
            term).</para></listitem> 
      </itemizedlist>

      <sect3 id="RCL.SEARCH.WILDCARDS.PATH">
        <title>Wildcards and path filtering</title>

        <para>Due to the way that &RCL; processes wildcards
          inside <literal>dir</literal> path filtering clauses, they
          will have a multiplicative effect on the query size. A clause
          containg wildcards in several paths elements, like, for
          example,
          <literal>dir:</literal><replaceable>/home/me/*/*/docdir</replaceable>,
          will almost certainly fail if your indexed tree is of any realistic
          size.</para>

        <para>Depending on the case, you may be able to work around
        the issue by specifying the paths elements more narrowly, with
          a constant prefix, or by using 2
          separate <literal>dir:</literal> clauses instead of multiple
          wildcards, as
          in <literal>dir:</literal><replaceable>/home/me</replaceable> <literal>dir:</literal><replaceable>docdir</replaceable>. The
          latter query is not equivalent to the initial one because it
          does not specify a number of directory levels, but that's
          the best we can do (and it may be actually more useful in
          some cases).</para>

      </sect3>

    </sect2> <!-- wildchars -->

      <sect2 id="RCL.SEARCH.ANCHOR">
        <title>Anchored searches</title>

        <para>Two characters are used to specify that a search hit should
        occur at the beginning or at the end of the
        text. <literal>^</literal> at the beginning of a term or phrase
        constrains the search to happen at the start, <literal>$</literal>
        at the end force it to happen at the end.</para>
        
        <para>As this function is implemented as a phrase search it is
        possible to specify a maximum distance at which the hit should
        occur, either through the controls of the advanced search panel, or
        using the query language, for example, as in:
        <programlisting>"^someterm"o10</programlisting> which would force
        <literal>someterm</literal> to be found within 10 terms of the
        start of the text. This can be combined with a field search as in
        <literal>somefield:"^someterm"o10</literal> or
        <literal>somefield:someterm$</literal>.</para>

        <para>This feature can also be used with an actual phrase search,
        but in this case, the distance applies to the whole phrase and
        anchor, so that, for example, <literal>bla bla my unexpected
        term</literal> at the beginning of the text would be a match for
        <literal>"^my term"o5</literal>.</para>

        <para>Anchored searches can be very useful for searches inside
        somewhat structured documents like scientific articles, in case
        explicit metadata has not been supplied (a most frequent case), for
        example for looking for matches inside the abstract or the list of
        authors (which occur at the top of the document).</para>


   </sect2>

   </sect1> <!-- wildchars and anchors -->

    <sect1 id="RCL.SEARCH.DESKTOP">
      <title>Desktop integration</title>

      <para>Being independant of the desktop type has its drawbacks: &RCL;
      desktop integration is minimal. However there are a few tools
      available:
      <itemizedlist>
          <listitem>
            <para>The <application>KDE</application> KIO Slave was
            described in a <link linkend="RCL.SEARCH.KIO">previous 
            section</link>.</para>
          </listitem>
        <listitem>
            <para>If you use a recent version of Ubuntu Linux, you may
             find the <ulink url="&WIKI;UnityLens">Ubuntu Unity
           Lens</ulink> module useful.</para>
          </listitem>
          <listitem>
            <para>There is also an independantly developed
                 <ulink
      url="http://kde-apps.org/content/show.php/recollrunner?content=128203">
            Krunner plugin</ulink>.</para>
          </listitem>
        </itemizedlist>
       </para>

       <para>Here follow a few other things that may help.</para>

      <sect2 id="RCL.SEARCH.SHORTCUT">
        <title>Hotkeying recoll</title>

        <para>It is surprisingly convenient to be able to show or hide the
          &RCL; GUI with a single keystroke. Recoll comes with a small
          Python script, based on the <application>libwnck</application> window
          manager interface library, which will allow you to do just
          this. The detailed instructions are on
          <ulink url="&WIKI;HotRecoll">this wiki page</ulink>.</para>

      </sect2>

      <sect2 id="RCL.KICKER-APPLET">
        <title>The KDE Kicker Recoll applet</title>

        <para>This is probably obsolete now. Anyway:</para>
        <para>The &RCL; source tree contains the source code to the
        <application>recoll_applet</application>, a small application derived
        from the <application>find_applet</application>. This can be used to
        add a small &RCL; launcher to the KDE panel.</para>

        <para>The applet is not automatically built with the main &RCL;
         programs, nor is it included with the main source distribution
        (because the KDE build boilerplate makes it relatively big). You can
        download its source from the recoll.org download page. Use the
        omnipotent <userinput>configure;make;make install</userinput>
        incantation to build and install.</para>
      
        <para>You can then add the applet to the panel by right-clicking the
        panel and choosing the <guilabel>Add applet</guilabel> entry.</para>

        <para>The <application>recoll_applet</application> has a small text
         window where you can type a &RCL; query (in query language form),
         and an icon which can be used to restrict the search to certain
         types of files. It is quite primitive, and launches a new recoll
         GUI instance every time (even if it is already running). You may
         find it useful anyway.</para>

      </sect2>

    </sect1> <!-- rcl.search.desktop -->

  </chapter> <!-- Search -->


    <chapter id="RCL.PROGRAM">
      <title>Programming interface</title>

      <para>&RCL; has an Application Programming Interface, usable both
        for indexing and searching, currently accessible from the
        <application>Python</application> language.</para>

      <para>Another less radical way to extend the application is to
        write input handlers for new types of documents.</para>

      <para>The processing of metadata attributes for documents
        (<literal>fields</literal>) is highly configurable.</para>



      <sect1 id="RCL.PROGRAM.FILTERS">
        <title>Writing a document input handler</title>
        
        <note><title>Terminology</title>The small programs or pieces
        of code which handle the processing of the different document
        types for &RCL; used to be called <literal>filters</literal>,
        which is still reflected in the name of the directory which
        holds them and many configuration variables. They were named
        this way because one of their primary functions is to filter
        out the formatting directives and keep the text
        content. However these modules may have other behaviours, and
        the term <literal>input handler</literal> is now progressively
        substituted in the documentation. <literal>filter</literal> is
        still used in many places though.</note>

        <para>&RCL; input handlers cooperate to translate from the multitude
        of input document formats, simple ones
        as <application>opendocument</application>, 
          <application>acrobat</application>), or compound ones such
          as <application>Zip</application>
          or <application>Email</application>, into the final &RCL;
          indexing input format, which is plain text.
          Most input handlers are executable
          programs or scripts. A few handlers are coded in C++ and live
          inside <command>recollindex</command>. This latter kind will not
          be described here.</para>

        <para>There are currently (1.18 and since 1.13) two kinds of
        external executable input handlers:
          <itemizedlist>
	    <listitem><para>Simple <literal>exec</literal> handlers
            run once and exit. They can be bare programs like
            <command>antiword</command>, or scripts using other
            programs. They are very simple to write, because they just
            need to print the converted document to the standard
            output. Their output can be plain text or HTML. HTML is
            usually preferred because it can store metadata fields and
            it allows preserving some of the formatting for the GUI
            preview.</para>
	    </listitem>
	    <listitem><para>Multiple <literal>execm</literal> handlers
	    can process multiple files (sparing the process startup
	    time which can be very significant), or multiple documents
	    per file (e.g.: for <application>zip</application> or
	    <application>chm</application> files). They communicate
	    with the indexer through a simple protocol, but are
	    nevertheless a bit more complicated than the older
	    kind. Most of new handlers are written in
	    <application>Python</application>, using a common module
	    to handle the protocol. There is an exception,
	    <command>rclimg</command> which is written in Perl. The
	    subdocuments output by these handlers can be directly
	    indexable (text or HTML), or they can be other simple or
	    compound documents that will need to be processed by
	    another handler.</para>
	    </listitem>
	  </itemizedlist>
        </para>

        <para>In both cases, handlers deal with regular file system
          files, and can process either a single document, or a
          linear list of documents in each file. &RCL; is responsible
          for performing up to date checks, deal with more complex
          embedding and other upper level issues.</para>

        <para>A simple handler returning a
          document in <literal>text/plain</literal> format, can transfer
          no metadata to the indexer. Generic metadata, like document
          size or modification date, will be gathered and stored by
          the indexer.</para>

        <para>Handlers that produce  <literal>text/html</literal>
          format can return an arbitrary amount of metadata inside HTML
          <literal>meta</literal> tags. These will be processed
          according to the directives found in 
          the <link linkend="RCL.PROGRAM.FIELDS">
            <filename>fields</filename> configuration
            file</link>.</para>

        <para>The handlers that can handle multiple documents per file
          return a single piece of data to identify each document inside
          the file. This piece of data, called
          an <literal>ipath element</literal> will be sent back by
          &RCL; to extract the document at query time, for previewing,
          or for creating a temporary file to be opened by a
          viewer.</para>  

        <para>The following section describes the simple
          handlers, and the next one gives a few explanations about
          the <literal>execm</literal> ones. You could conceivably
          write a simple handler with only the elements in the
          manual. This will not be the case for the other ones, for
          which you will have to look at the code.</para>

      <sect2 id="RCL.PROGRAM.FILTERS.SIMPLE">
        <title>Simple input handlers</title>

      <para>&RCL; simple handlers are usually shell-scripts, but this is in
        no way necessary. Extracting the text from the native format is the
        difficult part. Outputting the format expected by &RCL; is
        trivial. Happily enough, most document formats have translators or
        text extractors which can be called from the handler. In some cases
        the output of the translating program is completely appropriate,
        and no intermediate shell-script is needed.</para>

        <para>Input handlers are called with a single argument which is the
        source file name. They should output the result to stdout.</para>

      <para>When writing a handler, you should decide if it will output
      plain text or HTML. Plain text is simpler, but you will not be able
      to add metadata or vary the output character encoding (this will be
      defined in a configuration file). Additionally, some formatting may
      be easier to preserve when previewing HTML. Actually the deciding factor
      is metadata: &RCL; has a way to <link linkend="RCL.PROGRAM.FILTERS.HTML">
      extract metadata from the HTML header and use it for field 
      searches.</link>.</para>

      <para>The <envar>RECOLL_FILTER_FORPREVIEW</envar> environment
        variable (values <literal>yes</literal>, <literal>no</literal>)
        tells the handler if the operation is for indexing or
        previewing. Some handlers use this to output a slightly different
        format, for example stripping uninteresting repeated keywords (ie:
        <literal>Subject:</literal> for email) when indexing. This is not
        essential.</para>

      <para>You should look at one of the simple handlers, for example
        <command>rclps</command> for a starting point.</para>

        <para>Don't forget to make your handler executable before 
         testing !</para>

      </sect2>

      <sect2 id="RCL.PROGRAM.FILTERS.MULTIPLE">
        <title>"Multiple" handlers</title>

        <para>If you can program and want to write
          an <literal>execm</literal> handler, it should not be too
          difficult to make sense of one of the existing modules. For
          example, look at <command>rclzip</command> which uses Zip
          file paths as identifiers (<literal>ipath</literal>),
          and <command>rclics</command>, which uses an integer
          index. Also have a look at the comments inside
          the <filename>internfile/mh_execm.h</filename> file and
          possibly at the corresponding module.</para>

        <para><literal>execm</literal> handlers sometimes need to make
          a choice for the nature of the <literal>ipath</literal>
          elements that they use in communication with the
          indexer. Here are a few guidelines:
          <itemizedlist>
            <listitem><para>Use ASCII or UTF-8 (if the identifier is an
                integer print it, for example, like printf %d would
                do).</para></listitem>
            <listitem><para>If at all possible, the data should make some
              kind of sense when printed to a log file to help with 
                debugging.</para></listitem>
            <listitem><para>&RCL; uses a colon (<literal>:</literal>) as a
                separator to store a complex path internally (for
                deeper embedding). Colons inside
                the <literal>ipath</literal> elements output by a
                handler will be escaped, but would be a bad choice as a
                handler-specific separator (mostly, again, for
                debugging issues).</para></listitem>
          </itemizedlist>
          In any case, the main goal is that it should
          be easy for the handler to extract the target document, given
          the file name and the <literal>ipath</literal>
          element.</para>

        <para><literal>execm</literal> handlers will also produce
          a document with a null <literal>ipath</literal>
          element. Depending on the type of document, this may have
          some associated data (e.g. the body of an email message), or
          none (typical for an archive file). If it is empty, this
          document will be useful anyway for some operations, as the
          parent of the actual data documents.</para>
      </sect2>

      <sect2 id="RCL.PROGRAM.FILTERS.ASSOCIATION">
        <title>Telling &RCL; about the handler</title>

      <para>There are two elements that link a file to the handler which
      should process it: the association of file to MIME type and the
      association of a MIME type with a handler.</para>

      <para>The association of files to MIME types is mostly based on
        name suffixes. The types are defined inside the
        <link linkend="RCL.INSTALL.CONFIG.MIMEMAP">
        <filename>mimemap</filename> file</link>. Example:
<programlisting>

.doc = application/msword
</programlisting>
       If no suffix association is found for the file name, &RCL; will try
       to execute the <command>file -i</command> command to determine a
       MIME type.</para>

      <para>The association of file types to handlers is performed in
      the <link linkend="RCL.INSTALL.CONFIG.MIMECONF">
      <filename>mimeconf</filename> file</link>. A sample will probably be
      of better help than a long explanation:</para>
<programlisting>

[index]
application/msword = exec antiword -t -i 1 -m UTF-8;\
     mimetype = text/plain ; charset=utf-8

application/ogg = exec rclogg

text/rtf = exec unrtf --nopict --html; charset=iso-8859-1; mimetype=text/html

application/x-chm = execm rclchm
</programlisting>

      <para>The fragment specifies that:

      <itemizedlist>
	  <listitem><para><literal>application/msword</literal> files
            are processed by executing the <command>antiword</command>
            program, which outputs
            <literal>text/plain</literal> encoded in
            <literal>utf-8</literal>.</para> 
	  </listitem>
	  
	  <listitem><para><literal>application/ogg</literal> files are
            processed by the <command>rclogg</command> script, with
            default output type (<literal>text/html</literal>, with
            encoding specified in the header, or <literal>utf-8</literal>
            by default).</para>
	  </listitem>
	  
	  <listitem><para><literal>text/rtf</literal> is processed by
            <command>unrtf</command>, which outputs
            <literal>text/html</literal>. The 
            <literal>iso-8859-1</literal> encoding is specified because it
            is not the <literal>utf-8</literal> default, and not output by
            <command>unrtf</command> in the HTML header section.</para>
	  </listitem>
	  <listitem><para><literal>application/x-chm</literal> is processed
	      by a persistant handler. This is determined by the
	      <literal>execm</literal> keyword.</para>
	  </listitem>
	</itemizedlist>
       </para> 

      </sect2>

    <sect2 id="RCL.PROGRAM.FILTERS.HTML">
        <title>Input handler HTML output</title>

        <para>The output HTML could be very minimal like the following
        example:
          <programlisting>
&lt;html>
  &lt;head>
    &lt;meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
  &lt;/head>
  &lt;body>
   Some text content
  &lt;/body>
&lt;/html>
          </programlisting>
        </para>

        <para>You should take care to escape some
          characters inside the text by transforming them into
          appropriate entities. At the very minimum,
          "<literal>&amp;</literal>" should be transformed into
          "<literal>&amp;amp;</literal>", "<literal>&lt;</literal>"
          should be transformed into
          "<literal>&amp;lt;</literal>". This is not always properly
          done by translating programs which output HTML, and of
          course never by those which output plain text. </para>

        <para>When encapsulating plain text in an HTML body, 
          the display of a preview may be improved by enclosing the
          text inside <literal>&lt;pre></literal> tags.</para>

        <para>The character set needs to be specified in the
          header. It does not need to be UTF-8 (&RCL; will take care
          of translating it), but it must be accurate for good
          results.</para>

        <para>&RCL; will process <literal>meta</literal> tags inside
          the header as possible document fields candidates. Documents
          fields can be processed by the indexer in different ways,
          for searching or displaying inside query results. This is
          described in a <link linkend="RCL.PROGRAM.FIELDS">following
          section.</link>
        </para>

        <para>By default, the indexer will process the standard header
          fields if they are present: <literal>title</literal>,
          <literal>meta/description</literal>,
          and <literal>meta/keywords</literal> are both indexed and stored
          for query-time display.</para>

        <para>A predefined non-standard <literal>meta</literal> tag
          will also be processed by &RCL; without further
          configuration: if a <literal>date</literal> tag is present
          and has the right format, it will be used as the document
          date (for display and sorting), in preference to the file
          modification date. The date format should be as follows:
          <programlisting>
&lt;meta name="date" content="YYYY-mm-dd HH:MM:SS">
or
&lt;meta name="date" content="YYYY-mm-ddTHH:MM:SS">
          </programlisting>
          Example:
          <programlisting>
&lt;meta name="date" content="2013-02-24 17:50:00">
          </programlisting>
        </para>

        <para>Input handlers also have the possibility to "invent" field
          names. This should also be output as meta tags:</para>

        <programlisting>
&lt;meta name="somefield" content="Some textual data" /&gt;
</programlisting>

      <para>You can embed HTML markup inside the content of custom
        fields, for improving the display inside result lists. In this
        case, add a (wildly non-standard) <literal>markup</literal>
        attribute to tell &RCL; that the value is HTML and should not
        be escaped for display.</para>

        <programlisting>
&lt;meta name="somefield" markup="html" content="Some &lt;i>textual&lt;/i> data" /&gt;
</programlisting>

        <para>As written above, the processing of fields is described
          in a <link linkend="RCL.PROGRAM.FIELDS">further
          section</link>.</para> 

      </sect2>

    <sect2 id="RCL.PROGRAM.FILTERS.PAGES">
        <title>Page numbers</title>

        <para>The indexer will interpret <literal>^L</literal> characters
          in the handler output as indicating page breaks, and will record
          them. At query time, this allows starting a viewer on the right
          page for a hit or a snippet. Currently, only the PDF, Postscript
          and DVI handlers generate page breaks.</para>

      </sect2>

    </sect1>

    <sect1 id="RCL.PROGRAM.FIELDS">
        <title>Field data processing</title>

      <para><literal>Fields</literal> are named pieces of information
      in or about documents, like <literal>title</literal>,
      <literal>author</literal>, <literal>abstract</literal>.</para> 

      <para>The field values for documents can appear in several ways
      during indexing: either output by input handlers
      as <literal>meta</literal> fields in the HTML header section, or
      extracted from file extended attributes, or added as attributes
      of the <literal>Doc</literal> object when using the API, or
      again synthetized internally by &RCL;.</para>

      <para>The &RCL; query language allows searching for text in a
      specific field.</para>

      <para>&RCL; defines a number of default fields. Additional
      ones can be output by handlers, and described in the
      <filename>fields</filename> configuration file.</para>

      <para>Fields can be:</para>
      <itemizedlist>

        <listitem><para><literal>indexed</literal>, meaning that their
        terms are separately stored in inverted lists (with a specific
        prefix), and that a field-specific search is possible.</para>
        </listitem>

        <listitem><para><literal>stored</literal>, meaning that their
        value is recorded in the index data record for the document,
        and can be returned and displayed with search results.</para>
        </listitem>

      </itemizedlist>

      <para>A field can be either or both indexed and stored. This and 
      other aspects of fields handling is defined inside the
      <filename>fields</filename> configuration file.</para>

      <para>The sequence of events for field processing is as follows:
       <itemizedlist>
          <listitem><para>During indexing, 
          <command>recollindex</command> scans all <literal>meta</literal>
          fields in HTML documents (most document types are transformed
          into HTML at some point). It compares the name for each element
          to the configuration defining what should be done with fields
          (the <filename>fields</filename> file)</para>
          </listitem>
          <listitem><para>If the name for the <literal>meta</literal>
          element matches one for a field that should be indexed, the
          contents are processed and the terms are entered into the index
          with the prefix defined in the <filename>fields</filename>
          file.</para>
          </listitem>
          <listitem><para>If the name for the <literal>meta</literal> element
          matches one for a field that should be stored, the content of the
          element is stored with the document data record, from which it
          can be extracted and displayed at query time.</para>
          </listitem>
          <listitem><para>At query time, if a field search is performed, the
          index prefix is computed and the match is only performed against
          appropriately prefixed terms in the index.</para>
          </listitem>
          <listitem><para>At query time, the field can be displayed inside
          the result list by using the appropriate directive in the
          definition of the <link
          linkend="RCL.SEARCH.GUI.CUSTOM.RESLIST">result list paragraph
          format</link>. All fields are displayed on the fields screen of
          the preview window (which you can reach through the right-click
          menu). This is independant of the fact that the search which
          produced the results used the field or not.</para>  
          </listitem>
        </itemizedlist>
      </para>

      <para>You can find more information in the 
      <link linkend="RCL.INSTALL.CONFIG.FIELDS">section about the
      <filename>fields</filename> file</link>, or in comments inside the
      file.</para> 

      <para>You can also have a look at the 
       <ulink url="&WIKI;HandleCustomField">example on the Wiki</ulink>, 
      detailing how one could add a <emphasis>page count</emphasis> field
      to pdf documents for displaying inside result lists.</para>

    </sect1>


    <sect1 id="RCL.PROGRAM.API">
      <title>API</title>

    <sect2 id="RCL.PROGRAM.API.ELEMENTS">
      <title>Interface elements</title>

      <para>A few elements in the interface are specific and and need
      an explanation.</para>

      <variablelist>

        <varlistentry>
          <term>udi</term> <listitem><para>An udi (unique document
            identifier) identifies a document. Because of limitations
            inside the index engine, it is restricted in length (to
            200 bytes), which is why a regular URI cannot be used. The
            structure and contents of the udi is defined by the
            application and opaque to the index engine. For example,
            the internal file system indexer uses the complete
            document path (file path + internal path), truncated to
            length, the suppressed part being replaced by a hash
            value.</para> </listitem>
        </varlistentry>

        <varlistentry> 
          <term>ipath</term> 
          
          <listitem><para>This data value (set as a field in the Doc
          object) is stored, along with the URL, but not indexed by
          &RCL;. Its contents are not interpreted, and its use is up
          to the application. For example, the &RCL; internal file
          system indexer stores the part of the document access path
          internal to the container file (<literal>ipath</literal> in
          this case is a list of subdocument sequential numbers). url
          and ipath are returned in every search result and permit
          access to the original document.</para>
          </listitem>
        </varlistentry>

        <varlistentry> 
          <term>Stored and indexed fields</term> 
          
          <listitem><para>The <filename>fields</filename> file inside
          the &RCL; configuration defines which document fields are
          either "indexed" (searchable), "stored" (retrievable with
          search results), or both.</para>
          </listitem>
        </varlistentry>

      </variablelist>

      <para>Data for an external indexer, should be stored in a
        separate index, not the one for the &RCL; internal file system
        indexer, except if the latter is not used at all). The reason
        is that the main document indexer purge pass would remove all
        the other indexer's documents, as they were not seen during
        indexing. The main indexer documents would also probably be a
        problem for the external indexer purge operation.</para>

    </sect2>

    <sect2 id="RCL.PROGRAM.API.PYTHON">
      <title>Python interface</title>

      <sect3 id="RCL.PROGRAM.PYTHON.INTRO">
        <title>Introduction</title>

        <para>&RCL; versions after 1.11 define a Python programming
          interface, both for searching and indexing. The indexing
          portion has seen little use, but the searching one is used
          in the Recoll Ubuntu Unity Lens and Recoll Web UI.</para> 

        <para>The API is inspired by the Python database API
          specification. There were two major changes in recent &RCL;
          versions:
          <itemizedlist>
            <listitem>The basis for the &RCL; API changed from Python
              database API version 1.0 (&RCL; versions up to 1.18.1),
              to version 2.0 (&RCL; 1.18.2 and later).</listitem>
            <listitem>The <literal>recoll</literal> module became a
              package (with an internal <literal>recoll</literal>
              module) as of &RCL; version 1.19, in order to add more
              functions. For existing code, this only changes the way
              the interface must be imported.</listitem>
          </itemizedlist>
        </para>

        <para>We will mostly describe the new API and package
          structure here. A paragraph at the end of this section will
          explain a few differences and ways to write code
          compatible with both versions.</para>

        <para>The Python interface can be found in the source package,
          under <filename>python/recoll</filename>.</para>

	<para>The <filename>python/recoll/</filename> directory
	  contains the usual <filename>setup.py</filename>. After
	  configuring the main &RCL; code, you can use the script to
	  build and install the Python module:
          <screen>
            <userinput>cd recoll-xxx/python/recoll</userinput>
            <userinput>python setup.py build</userinput>
            <userinput>python setup.py install</userinput>
          </screen>
        </para> 

        <para>The normal &RCL; installer installs the Python
          API along with the main code.</para>

        <para>When installing from a repository, and depending on the
          distribution, the Python API can sometimes be found in a
          separate package.</para>

      </sect3>

      <sect3 id="RCL.PROGRAM.PYTHON.PACKAGE">
        <title>Recoll package</title>
        
        <para>The <literal>recoll</literal> package contains two
          modules:
          <itemizedlist>
            <listitem><para>The <literal>recoll</literal> module contains
                functions and classes used to query (or update) the
                index.</para></listitem> 
            <listitem><para>The <literal>rclextract</literal> module contains
                functions and classes used to access document
                data.</para></listitem> 
          </itemizedlist>
        </para>            
      </sect3>

      <sect3 id="RCL.PROGRAM.PYTHON.RECOLL">
        <title>The recoll module</title>

        <sect4 id="RCL.PROGRAM.PYTHON.RECOLL.FUNCTIONS">
          <title>Functions</title>

          <variablelist>
            <varlistentry>
              <term>connect(confdir=None, extra_dbs=None,
                writable = False)</term>
              <listitem>
                The <literal>connect()</literal> function connects to
                one or several &RCL; index(es) and returns
                a <literal>Db</literal> object.
                <itemizedlist>
                  <listitem><literal>confdir</literal> may specify
                    a configuration directory. The usual defaults
                    apply.</listitem> 
                  <listitem><literal>extra_dbs</literal> is a list of
                  additional indexes (Xapian directories). </listitem>
                  <listitem><literal>writable</literal> decides if
                    we can index new data through this
                    connection.</listitem>
                </itemizedlist> 
                This call initializes the recoll module, and it should
                always be performed before any other call or object creation.
              </listitem>
          </varlistentry>

          </variablelist>
        </sect4>


      <sect4 id="RCL.PROGRAM.PYTHON.RECOLL.CLASSES">
        <title>Classes</title>
        
        <sect5 id="RCL.PROGRAM.PYTHON.RECOLL.CLASSES.DB">
          <title>The Db class</title>

          <para>A Db object is created by
            a <literal>connect()</literal> call and holds a 
            connection to a Recoll index.</para>
          <variablelist>
            <title>Methods</title>
            <varlistentry>
              <term>Db.close()</term>
              <listitem>Closes the connection. You can't do anything
                with the <literal>Db</literal> object after
                this.</listitem>
            </varlistentry>
            <varlistentry>
              <term>Db.query(), Db.cursor()</term> <listitem>These
                aliases return a blank <literal>Query</literal> object
                for this index.</listitem>
            </varlistentry>

            <varlistentry>
              <term>Db.setAbstractParams(maxchars,
              contextwords)</term> <listitem>Set the parameters used
              to build snippets (sets of keywords in context text
              fragments). <literal>maxchars</literal> defines the
                maximum total size of the abstract. 
                <literal>contextwords</literal> defines how many
                terms are shown around the keyword.</listitem>
            </varlistentry>

            <varlistentry>
              <term>Db.termMatch(match_type, expr, field='',
	        maxlen=-1, casesens=False, diacsens=False, lang='english')
                </term> 
              <listitem>Expand an expression against the
                index term list. Performs the basic function from the
                GUI term explorer tool. <literal>match_type</literal>
                can be either
                of <literal>wildcard</literal>, <literal>regexp</literal>
                or <literal>stem</literal>. Returns a list of terms
                expanded from the input expression.
              </listitem>
            </varlistentry>

          </variablelist>

        </sect5>


        <sect5 id="RCL.PROGRAM.PYTHON.RECOLL.CLASSES.QUERY">
          <title>The Query class</title>

          <para>A <literal>Query</literal> object (equivalent to a
            cursor in the Python DB API) is created by
            a <literal>Db.query()</literal> call. It is used to
            execute index searches.</para>

          <variablelist>
            <title>Methods</title>

            <varlistentry>
              <term>Query.sortby(fieldname, ascending=True)</term>
              <listitem>Sort results
                by <replaceable>fieldname</replaceable>, in ascending
                or descending order. Must be called before executing
                the search.</listitem>
            </varlistentry>
  
            <varlistentry>
              <term>Query.execute(query_string, stemming=1, 
                stemlang="english")</term>
              <listitem>Starts a search
              for <replaceable>query_string</replaceable>, a &RCL;
              search language string.</listitem>
            </varlistentry>

            <varlistentry>
              <term>Query.executesd(SearchData)</term>
              <listitem>Starts a search for the query defined by the
                SearchData object.</listitem>
            </varlistentry>

            <varlistentry>
              <term>Query.fetchmany(size=query.arraysize)</term> 
              
              <listitem>Fetches
                the next <literal>Doc</literal> objects in the current
                search results, and returns them as an array of the
                required size, which is by default the value of
                the <literal>arraysize</literal> data member.</listitem>
            </varlistentry>

            <varlistentry>
              <term>Query.fetchone()</term>
              <listitem>Fetches the next <literal>Doc</literal> object
                from the current search results.</listitem>
            </varlistentry>

            <varlistentry>
              <term>Query.close()</term>
              <listitem>Closes the query. The object is unusable
              after the call.</listitem>
            </varlistentry>

            <varlistentry>
              <term>Query.scroll(value, mode='relative')</term>
              <listitem>Adjusts the position in the current result
                set. <literal>mode</literal> can
                be <literal>relative</literal>
                or <literal>absolute</literal>. </listitem>
            </varlistentry>

            <varlistentry>
              <term>Query.getgroups()</term>
              <listitem>Retrieves the expanded query terms as a list
                of pairs. Meaningful only after executexx In each
                pair, the first entry is a list of user terms (of size
                one for simple terms, or more for group and phrase
                clauses), the second a list of query terms as derived
                from the user terms and used in the Xapian
                Query.</listitem>
            </varlistentry>
            
            <varlistentry>
              <term>Query.getxquery()</term>
            <listitem>Return the Xapian query description as a Unicode string.
              Meaningful only after executexx.</listitem>
            </varlistentry>

            <varlistentry>
              <term>Query.highlight(text, ishtml = 0, methods = object)</term>
            <listitem>Will insert &lt;span "class=rclmatch">,
            &lt;/span> tags around the match areas in the input text
              and return the modified text.  <literal>ishtml</literal>
              can be set to indicate that the input text is HTML and
              that HTML special characters should not be escaped.
              <literal>methods</literal> if set should be an object
              with methods startMatch(i) and endMatch() which will be
              called for each match and should return a begin and end
              tag</listitem>
            </varlistentry>

            <varlistentry>
              <term>Query.makedocabstract(doc, methods = object))</term>
              <listitem>Create a snippets abstract
                for <literal>doc</literal> (a <literal>Doc</literal>
                object) by selecting text around the match terms.
                If methods is set, will also perform highlighting. See
                the highlight method.
              </listitem>
            </varlistentry>
   
            <varlistentry>
              <term>Query.__iter__() and Query.next()</term>
              <listitem>So that things like <literal>for doc in
                  query:</literal> will work.</listitem>
            </varlistentry>
          </variablelist>

          <variablelist>
            <title>Data descriptors</title>

            <varlistentry><term>Query.arraysize</term> <listitem>Default
                number of records processed by fetchmany (r/w).</listitem> 
            </varlistentry>
            <varlistentry><term>Query.rowcount</term><listitem>Number of
                records returned by the last execute.</listitem></varlistentry>
            <varlistentry><term>Query.rownumber</term><listitem>Next index
                to be fetched from results. Normally increments after
                each fetchone() call, but can be set/reset before the
                call to effect seeking (equivalent to
                using <literal>scroll()</literal>). Starts at
                0.</listitem> 
            </varlistentry>

          </variablelist>

        </sect5>


        <sect5 id="RCL.PROGRAM.PYTHON.RECOLL.CLASSES.DOC">
          <title>The Doc class</title>

          <para>A <literal>Doc</literal> object contains index data
            for a given document. The data is extracted from the
            index when searching, or set by the indexer program when
            updating. The Doc object has many attributes to be read or
            set by its user. It matches exactly the Rcl::Doc C++
            object. Some of the attributes are predefined, but,
            especially when indexing, others can be set, the name of
            which will be processed as field names by the indexing
            configuration.  Inputs can be specified as Unicode or
            strings. Outputs are Unicode objects. All dates are
            specified as Unix timestamps, printed as strings. Please
            refer to the <filename>rcldb/rcldoc.h</filename> C++ file
            for a description of the predefined attributes.</para>

          <para>At query time, only the fields that are defined
            as <literal>stored</literal> either by default or in
            the <filename>fields</filename> configuration file will be
            meaningful in the <literal>Doc</literal>
            object. Especially this will not be the case for the
            document text. See the <literal>rclextract</literal>
            module for accessing document contents.</para> 

          <variablelist>
            <title>Methods</title>

            <varlistentry>
              <term>get(key), [] operator</term>
              <listitem>Retrieve the named doc attribute</listitem>
            </varlistentry>
            <varlistentry><term>getbinurl()</term><listitem>Retrieve
                the URL in byte array format (no transcoding), for use as
                parameter to a system call.</listitem>
            </varlistentry>
            <varlistentry>
              <term>items()</term>
              <listitem>Return a dictionary of doc object
              keys/values</listitem> 
            </varlistentry>
            <varlistentry>
              <term>keys()</term>
              <listitem>list of doc object keys (attribute
              names).</listitem>
            </varlistentry>
          </variablelist>

        </sect5> <!-- Doc -->

        <sect5 id="RCL.PROGRAM.PYTHON.RECOLL.CLASSES.SEARCHDATA">
          <title>The SearchData class</title>

          <para>A <literal>SearchData</literal> object allows building
            a query by combining clauses, for execution
            by <literal>Query.executesd()</literal>. It can be used
            in replacement of the query language approach. The
            interface is going to change a little, so no detailed doc
            for now...</para>

          <variablelist>
            <title>Methods</title>

            <varlistentry>
              <term>addclause(type='and'|'or'|'excl'|'phrase'|'near'|'sub',
                qstring=string, slack=0, field='', stemming=1,
                subSearch=SearchData)</term>
              <listitem></listitem>
            </varlistentry>
          </variablelist>

        </sect5> <!-- SearchData -->

      </sect4> <!-- recoll.classes -->
      </sect3> <!-- Recoll module -->

      <sect3 id="RCL.PROGRAM.PYTHON.RCLEXTRACT">
        <title>The rclextract module</title>

        <para>Index queries do not provide document content (only a
          partial and unprecise reconstruction is performed to show the
          snippets text). In order to access the actual document data, 
          the data extraction part of the indexing process
          must be performed (subdocument access and format
          translation). This is not trivial in
          general. The <literal>rclextract</literal> module currently
          provides a single class which can be used to access the data
          content for result documents.</para>

        <sect4 id="RCL.PROGRAM.PYTHON.RCLEXTRACT.CLASSES">
          <title>Classes</title>
        
          <sect5 id="RCL.PROGRAM.PYTHON.RECOLL.CLASSES.EXTRACTOR">
            <title>The Extractor class</title>

            <variablelist>
              <title>Methods</title>

              <varlistentry>
                <term>Extractor(doc)</term>
                <listitem>An <literal>Extractor</literal> object is
                  built from a <literal>Doc</literal> object, output
                  from a query.</listitem>
              </varlistentry>
              <varlistentry>
                <term>Extractor.textextract(ipath)</term>
                <listitem>Extract document defined
                by <replaceable>ipath</replaceable> and return
                a <literal>Doc</literal> object. The doc.text field
                has the document text converted to either text/plain or
                text/html according to doc.mimetype. The typical use
                would be as follows:
                  <programlisting>
qdoc = query.fetchone()
extractor = recoll.Extractor(qdoc)
doc = extractor.textextract(qdoc.ipath)
# use doc.text, e.g. for previewing
</programlisting>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>Extractor.idoctofile(ipath, targetmtype, outfile='')</term>
                <listitem>Extracts document into an output file,
                  which can be given explicitly or will be created as a
                  temporary file to be deleted by the caller. Typical use:
                  <programlisting>
qdoc = query.fetchone()
extractor = recoll.Extractor(qdoc)
filename = extractor.idoctofile(qdoc.ipath, qdoc.mimetype)</programlisting>

                </listitem>
              </varlistentry>

          </variablelist>

          </sect5> <!-- Extractor class -->
        </sect4> <!-- rclextract classes -->
      </sect3> <!-- rclextract module -->



      <sect3 id="RCL.PROGRAM.PYTHON.EXAMPLES">
        <title>Example code</title>

        <para>The following sample would query the index with a user
        language string. See the <filename>python/samples</filename>
          directory inside the &RCL; source for other
          examples. The <filename>recollgui</filename> subdirectory
          has a very embryonic GUI which demonstrates the
          highlighting and data extraction functions.</para>

        <programlisting>
#!/usr/bin/env python
<![CDATA[
from recoll import recoll

db = recoll.connect()
db.setAbstractParams(maxchars=80, contextwords=4)

query = db.query()
nres = query.execute("some user question")
print "Result count: ", nres
if nres > 5:
    nres = 5
for i in range(nres):
    doc = query.fetchone()
    print "Result #%d" % (query.rownumber,)
    for k in ("title", "size"):
        print k, ":", getattr(doc, k).encode('utf-8')
    abs = db.makeDocAbstract(doc, query).encode('utf-8')
    print abs
    print

]]>
</programlisting>

      </sect3>

      <sect3 id="RCL.PROGRAM.PYTHON.COMPAT">
        <title>Compatibility with the previous version</title>

        <para>The following code fragments can be used to ensure that
          code can run with both the old and the new API (as long as it
          does not use the new abilities of the new API of
          course).</para>

        <para>Adapting to the new package structure:</para>
        <programlisting>
<![CDATA[
try:
    from recoll import recoll
    from recoll import rclextract
    hasextract = True
except:
    import recoll
    hasextract = False
]]>
</programlisting>

        <para>Adapting to the change of nature of
          the <literal>next</literal> <literal>Query</literal>
          member. The same test can be used to choose to use
          the <literal>scroll()</literal> method (new) or set
          the <literal>next</literal> value (old).</para>

        <programlisting>
<![CDATA[
       rownum = query.next if type(query.next) == int else \
                 query.rownumber
]]>
</programlisting>

      </sect3> <!-- compat with previous version -->
    </sect2>
    </sect1>
  </chapter>


  <chapter id="RCL.INSTALL">
    <title>Installation and configuration</title>

    <sect1 id="RCL.INSTALL.BINARY">
      <title>Installing a binary copy</title>

	  
      <para>&RCL; binary copies are always distributed as regular
      packages for your system. They can be obtained either through
      the system's normal software distribution framework (e.g.
      <application>Debian/Ubuntu apt</application>,
	   <application>FreeBSD</application> ports, etc.), or from some type
	   of "backports" repository providing versions newer than the standard
	   ones, or found on the &RCL; WEB site in some
	   cases.</para>

	   <para>There used to exist another form of binary install, as
	   pre-compiled source trees, but these are just less convenient than
	   the packages and don't exist any more.</para>

	   <para>The package management tools will usually automatically
	   deal with hard dependancies for packages obtained from a proper
	   package repository. You will have to deal with them by hand for
	   downloaded packages (for example, when <command>dpkg</command>
	   complains about missing dependancies).</para>

      <para>In all cases, you will have to check or install <link
      linkend="RCL.INSTALL.EXTERNAL">supporting applications</link>
      for the file types that you want to index beyond those that are
      natively processed by &RCL; (text, HTML, email files, and a few
      others).</para>

      <para>You should also maybe have a look at the 
      <link linkend="RCL.INSTALL.CONFIG">configuration section</link>
      (but this may not be necessary for a quick test with default
      parameters). Most parameters can be more conveniently set from the
      GUI interface.</para>

    </sect1>

    <sect1 id="RCL.INSTALL.EXTERNAL">
      <title>Supporting packages</title>

      <para>&RCL; uses external applications to index some file
        types. You need to install them for the file types that you wish to
        have indexed (these are run-time optional dependencies. None is
        needed for building or running &RCL; except for indexing their
        specific file type).</para>

      <para>After an indexing pass, the commands that were found
	missing can be displayed from the <command>recoll</command>
	<guilabel>File</guilabel> menu. The list is stored in the
	<filename>missing</filename> text file inside the configuration
	directory.</para>

      <para>A list of common file types which need external
        commands follows. Many of the handlers need the
        <command>iconv</command> command, which is not always listed as a
        dependancy.</para> 

      <para>Please note that, due to the relatively dynamic nature of this
	information, the most up to date version is now kept on &RCLAPPS;
	along with links to the home pages or best source/patches pages,
	and misc tips. The list below is not updated often and may be quite
	stale.</para>

      <para>For many Linux distributions, most of the commands listed can
        be installed from the package repositories. However, the packages
        are sometimes outdated, or not the best version for &RCL;, so you
        should take a look at &RCLAPPS; if a file
        type is important to you.</para>

      <para>As of &RCL; release 1.14, a number of XML-based formats that
        were handled by ad hoc handler code now use the
        <command>xsltproc</command> command, which usually comes with  
	  <application>libxslt</application>. These are: abiword, fb2
	  (ebooks), kword, openoffice, svg.</para> 

      <para>Now for the list:</para>
      <itemizedlist>

        <listitem><para>Openoffice files need <command>unzip</command> and
        <command>xsltproc</command>.</para></listitem>

        <listitem><para>PDF files need <command>pdftotext</command>
        which is part of <application>Poppler</application> (usually
        comes with the <literal>poppler-utils</literal>
        package). Avoid the original one from 
        <application>Xpdf</application>.</para></listitem>

        <listitem><para>Postscript files need <command>pstotext</command>. 
            The original version has an issue with shell
            character in file names, which is corrected in recent
            packages. See &RCLAPPS; for more detail.</para>
          </listitem>

        <listitem><para>MS Word needs
        <command>antiword</command>. It is also useful to have
        <command>wvWare</command> installed as it may be 
        be used as a fallback for some files which
        <command>antiword</command> does not handle.</para></listitem>

        <listitem><para>MS Excel and PowerPoint are processed by
        internal <command>Python</command> handlers.</para></listitem>

        <listitem><para>MS Open XML (docx) needs <command>
         xsltproc</command>.</para></listitem>

        <listitem><para>Wordperfect files need <command>wpd2html</command>
        from the <application>libwpd</application> (or
        <application>libwpd-tools</application> on Ubuntu)
        package.</para></listitem>

        <listitem><para>RTF files need <command>unrtf</command>,
        which, in its older versions, has much trouble with
        non-western character sets. Many Linux distributions carry
        outdated <command>unrtf</command> versions. Check
        &RCLAPPS; for details.</para></listitem>

        <listitem><para>TeX files need <command>untex</command> or
        <command>detex</command>. Check &RCLAPPS; for sources if it's not
        packaged for your distribution.</para></listitem>

        <listitem><para>dvi files need <command>dvips</command>.</para>
        </listitem>

        <listitem><para>djvu files need <command>djvutxt</command> and
        <command>djvused</command> from the
        <application>DjVuLibre</application> package.</para></listitem>
          
        <listitem><para>Audio files: &RCL; releases 1.14 and later use
        a single <application>Python</application> handler based 
        on <application>mutagen</application> for all audio file
        types.</para>
	</listitem>

        <listitem><para>Pictures: &RCL; uses the 
         <application>Exiftool</application>
         <application>Perl</application> package to extract tag
         information. Most image file formats are supported. Note that
         there may not be much interest in indexing the technical tags
         (image size, aperture, etc.). This is only of interest if you
         store personal tags or textual descriptions inside the image
         files.</para></listitem>

	<listitem><para>chm: files in Microsoft help format need Python and
          the <application>pychm</application> module (which needs 
          <application>chmlib</application>).</para></listitem>

	<listitem><para>ICS: up to &RCL; 1.13, iCalendar files need 
        <application>Python</application>
	and the <application>icalendar</application>
	module. <application>icalendar</application> is not needed for newer
	versions,  which use internal code.</para></listitem> 

	<listitem><para>Zip archives need <application>Python</application>
	(and the standard zipfile module). </para></listitem>

	<listitem><para>Rar archives need
	<application>Python</application>, the
	<application>rarfile</application> Python module and the
	<command>unrar</command> utility.</para></listitem>

	<listitem><para>Midi karaoke files need
	<application>Python</application> and the 
        <ulink url="http://pypi.python.org/pypi/midi/0.2.1">
         <application>Midi module</application></ulink></para>
        </listitem>

        <listitem><para>Konqueror webarchive format with Python (uses the
        Tarfile module).</para></listitem>

        <listitem><para>Mimehtml web archive format (support based on
        the email handler, which introduces some mild weirdness, but
        still usable).</para></listitem>

        </itemizedlist>

        <para>Text, HTML, email folders, and Scribus files are
        processed internally. <application>Lyx</application> is used to
        index Lyx files. Many handlers need <command>iconv</command> and the
        standard <command>sed</command> and <command>awk</command>.
        </para>

    </sect1>


      <sect1 id="RCL.INSTALL.BUILDING">
      <title>Building from source</title>

      <sect2 id="RCL.INSTALL.BUILDING.PREREQS">
        <title>Prerequisites</title>

        <para>If you can install any or all of the following through
          the package manager for your system, all the
          better. Especially <application>Qt</application> is a very
          big piece of software, but you will most probably be able to
          find a binary package.</para>

        <para>You may have to compile &XAP; but this is easy.</para>

        <para>The shopping list:</para>
        <itemizedlist>

          <listitem><para>C++ compiler. Up to &RCL; version 1.13.04,
              its absence can manifest itself by strange messages
              about a missing iconv_open.</para>
          </listitem>

          <listitem><para>Development files
              for <ulink url="http://www.xapian.org"> <application>Xapian
                  core</application></ulink>.</para> 
            <important>
              <para>If you are
                building Xapian for an older CPU (before Pentium 4 or Athlon
                64), you need to add the <option>--disable-sse</option> flag
                to the configure command. Else all Xapian application will
                crash with an <literal>illegal instruction</literal>
                error.</para> 
            </important>
          </listitem>

          <listitem>
	    <para>Development files for 
              <ulink url="http://qt-project.org/downloads">
                <application>Qt 4</application> </ulink>. &RCL; has not been
              tested with <application>Qt 5</application> yet. &RCL; 1.15.9
              was the last version to support <application>Qt 3</application>.
              If you do not want to install or build
              the <application>Qt Webkit</application> module, &RCL;
              has a configuration option to disable its use (see further).
            </para> 
          </listitem>

        <listitem>
	  <para>Development files for <application>X11</application> and
	    <application>zlib</application>.</para>
        </listitem>

        <listitem>
          <para>You may also need 
            <ulink url="http://www.gnu.org/software/libiconv/">
              libiconv</ulink>. On <application>Linux</application>
              systems, the iconv interface is part of libc and you should not
            need to do anything special.</para>
          </listitem>

        </itemizedlist>

        <para>Check the <ulink url="http://www.recoll.org/download.html">
         &RCL; download page</ulink> for up to date version
         information.</para>

      </sect2>

      <sect2 id="RCL.INSTALL.BUILDING.BUILD">
        <title>Building</title>

      <para>&RCL; has been built on Linux, FreeBSD, Mac OS X, and Solaris,
      most versions after 2005 should be ok, maybe some older ones too
      (Solaris 8 is ok). If you build on another system, and
        need to modify things,
        <ulink url="mailto:jfd@recoll.org">I would
        very much welcome patches</ulink>.</para>


        <formalpara><title>Configure options:</title>
	  <para>
        <itemizedlist>

	  <listitem><para><option>--without-aspell</option> 
            will disable the code for phonetic matching of search
            terms. </para></listitem>

	  <listitem><para><option>--with-fam</option> or
            <option>--with-inotify</option> will enable the code for
            real time indexing. Inotify support is enabled by default on
            recent Linux systems.</para></listitem>

	  <listitem><para><option>--with-qzeitgeist</option> will
	      enable sending <application>Zeitgeist</application>
	      events about the visited search results, and needs
	      the <application>qzeitgeist</application>
	      package.</para></listitem> 

          <listitem><para><option>--disable-webkit</option> is available
              from version 1.17 to implement the result list with a
              <application>Qt</application> QTextBrowser instead of a
              WebKit widget if you do not or can't depend on the
              latter.</para></listitem>

          <listitem><para><option>--disable-idxthreads</option> is available
              from version 1.19 to suppress multithreading inside the
              indexing process. You can also use the run-time
              configuration to restrict <command>recollindex</command>
              to using a single thread, but the compile-time option
              may disable a few more unused locks. This only applies
              to the use of multithreading for the core index
              processing (data input). The &RCL; monitor mode always
              uses at least two threads of execution.</para></listitem>

	  <listitem><para><option>--disable-python-module</option> will 
              avoid building the <application>Python</application>
              module.</para></listitem>

	  <listitem><para><option>--disable-xattr</option> will prevent
 	      fetching data from file extended attributes. Beyond a
 	      few standard attributes, fetching extended attributes
 	      data can only be useful is some application stores data
 	      in there, and also needs some simple configuration (see
 	      comments in the <filename>fields</filename> configuration
	      file).</para></listitem>

	  <listitem><para><option>--enable-camelcase</option> will enable
 	    splitting <replaceable>camelCase</replaceable> words. This
	    is not enabled by default as it has the unfortunate
	    side-effect of making some phrase searches quite
	    confusing: ie, <literal>"MySQL manual"</literal> would be
	    matched by <literal>"MySQL manual"</literal> and
	    <literal>"my sql manual"</literal> but not <literal>"mysql
	    manual"</literal> (only inside phrase searches).</para>
	  </listitem>

	  <listitem><para><option>--with-file-command</option> Specify
	    the version of the 'file' command to use (ie:
            --with-file-command=/usr/local/bin/file). Can be useful to
            enable the gnu version on systems where the native one is
            bad.</para> </listitem>

	  <listitem><para><option>--disable-qtgui</option> Disable the Qt
	    interface. Will allow building the indexer and the command line
	    search program in absence of a Qt environment.</para> 
	  </listitem>

	  <listitem><para><option>--disable-x11mon</option> Disable
	    <application>X11</application> connection monitoring
	    inside recollindex. Together with --disable-qtgui, this
	    allows building recoll without
	    <application>Qt</application> and
	    <application>X11</application>.</para> </listitem>

	  <listitem><para><option>--disable-pic</option> will compile
	      &RCL; with position-dependant code. This is incompatible with
	      building the KIO or the <application>Python</application>
	      or <application>PHP</application> extensions, but might
	      yield very marginally faster code.</para></listitem>

	  <listitem><para>Of course the usual 
	  <application>autoconf</application> <command>configure</command>
	  options, like <option>--prefix</option> apply.</para> 
	  </listitem>
         </itemizedlist>
         </para>
	</formalpara>

      <para>Normal procedure:</para>
      <screen>
        <userinput>cd recoll-xxx</userinput>
        <userinput>./configure</userinput>
        <userinput>make</userinput>
        <userinput>(practices usual hardship-repelling invocations)</userinput>
      </screen>


      <para>There is little auto-configuration. The
        <command>configure</command> script will mainly link one of
        the system-specific files in the <filename>mk</filename>
        directory to <filename>mk/sysconf</filename>. If your system
        is not known yet, it will tell you as much, and you may want
        to manually copy and modify one of the existing files (the new
        file name should be the output of <command>uname</command>
        <option>-s</option>).</para> 
      
      <sect3 id="RCL.INSTALL.BUILDING.BUILD.SOLARIS">
	<title>Building on Solaris</title>

	<para>We did not test building the GUI on Solaris for recent
	  versions. You will need at least Qt 4.4. There are some hints
	  on <ulink url="http://www.recoll.org/download-1.14.html">an old
	    web site page</ulink>, they may still be valid.</para>

	<para>Someone did test the 1.19 indexer and Python module build,
	  they do work, with a few minor glitches. Be sure to use
	  GNU <command>make</command> and <command>install</command>.</para> 
	</sect3>

      </sect2>

      <sect2 id="RCL.INSTALL.BUILDING.INSTALL">
        <title>Installation</title>
      
      <para>Either type <userinput>make install</userinput> or execute
      <userinput>recollinstall
      <replaceable>prefix</replaceable></userinput>, in the root 
        of the source tree. This will copy the commands to
        <filename><replaceable>prefix</replaceable>/bin</filename>
        and the sample configuration files, scripts and other shared
        data to
        <filename><replaceable>prefix</replaceable>/share/recoll</filename>.</para>
        <para>If the installation prefix given to
        <command>recollinstall</command> is different from either the 
	system default or the value which was
        specified when executing <command>configure</command> (as in 
	<userinput>configure --prefix /some/path</userinput>), you
        will have to set the <envar>RECOLL_DATADIR</envar>
        environment variable to indicate where the shared data is to
        be found (ie for (ba)sh: 
	<userinput>export RECOLL_DATADIR=/some/path/share/recoll</userinput>).
	</para> 

        <para>You can then proceed to <link
       linkend="RCL.INSTALL.CONFIG">configuration</link>. </para>

      </sect2>
    </sect1>

    <sect1 id="RCL.INSTALL.CONFIG">
      <title>Configuration overview</title>

      <para>Most of the parameters specific to the
        <command>recoll</command> GUI are set through the
        <guilabel>Preferences</guilabel> menu and stored in the standard Qt
        place (<filename>$HOME/.config/Recoll.org/recoll.conf</filename>).
        You probably do not want to edit this by hand.</para>

      <para>&RCL; indexing options are set inside text configuration
        files located in a configuration directory. There can be
        several such directories, each of which defines the parameters
        for one index.</para>

      <para>The configuration files can be edited by hand or through
        the <guilabel>Index configuration</guilabel> dialog 
        (<guilabel>Preferences</guilabel> menu). The GUI tool will try
        to respect your formatting and comments as much as possible,
        so it is quite possible to use both ways.</para>

      <para>The most accurate documentation for the
        configuration parameters is given by comments inside the default
        files, and we will just give a general overview here.</para>

      <para>By default, for each index, there are two sets of
        configuration files. System-wide configuration files are kept
        in a directory named
        like <filename>/usr/[local/]share/recoll/examples</filename>,
        and define default values, shared by all indexes. For each
        index, a parallel set of files defines the customized
        parameters.</para>

      <para>In addition (as of &RCL; version 1.19.7), it is possible
        to specify two additional configuration directories which will
        be stacked before and after the user configuration
        directory. These are defined by
        the <envar>RECOLL_CONFTOP</envar>
        and <envar>RECOLL_CONFMID</envar> environment
        variables. Values from configuration files inside the top
        directory will override user ones, values from configuration
        files inside the middle directory will override system ones
        and be overriden by user ones. These two variables may be of
        use to applications which augment &RCL; functionality, and
        need to add configuration data without disturbing the user's
        files. Please note that the two, currently single, values will
        probably be interpreted as colon-separated lists in the
        future: do not use colon characters inside the directory
        paths.</para>

      <para>The default location of the configuration is the
        <filename>.recoll</filename>
        directory in your home. Most people will only use this
        directory.</para> 

      <para>This location can be changed, or others can be added with the
        <envar>RECOLL_CONFDIR</envar> environment variable or the
        <option>-c</option> option parameter to <command>recoll</command> and
        <command>recollindex</command>.</para>

      <para>If the <filename>.recoll</filename> directory does not
        exist when <command>recoll</command> or
        <command>recollindex</command> are started, it will be created
        with a set of empty configuration files.
        <command>recoll</command> will give you a chance to edit the
        configuration file before starting
        indexing. <command>recollindex</command> will proceed
        immediately. To avoid mistakes, the automatic directory
        creation will only occur for the
       default location, not if <option>-c</option> or
       <envar>RECOLL_CONFDIR</envar> were used (in the latter
       cases, you will have to create the directory).</para>
      

        <para>All configuration files share the same format. For
        example, a short extract of the main configuration file might
        look as follows:</para> 
        <programlisting>
        # Space-separated list of directories to index.
        topdirs =  ~/docs /usr/share/doc

        [~/somedirectory-with-utf8-txt-files]
        defaultcharset = utf-8
        </programlisting>

        <para>There are three kinds of lines: </para>
        <itemizedlist>
          <listitem><para>Comment (starts with
          <emphasis>#</emphasis>) or empty.</para> 
          </listitem>
          <listitem><para>Parameter affectation (<emphasis>name =
          value</emphasis>).</para> 
          </listitem>
          <listitem><para>Section definition
          ([<emphasis>somedirname</emphasis>]).</para> 
          </listitem>
        </itemizedlist>

        <para>Depending on the type of configuration file, section
        definitions either separate groups of parameters or allow
        redefining some parameters for a directory sub-tree. They stay
        in effect until another section definition, or the end of
        file, is encountered. Some of the parameters used for indexing
        are looked up hierarchically from the current directory
        location upwards. Not all parameters can be meaningfully
        redefined, this is specified for each in the next
        section. </para>

        <para>When found at the beginning of a file path, the tilde
        character (~) is expanded to the name of the user's home
        directory, as a shell would do.</para> 
        
        <para>White space is used for separation inside  lists.
        List elements with embedded spaces can be quoted using
        double-quotes.</para>

      <formalpara>
        <title>Encoding issues</title>
        <para>Most of the configuration parameters are plain ASCII. Two
        particular sets of values may cause encoding issues:</para>
      </formalpara>
      <para>
      <itemizedlist>
        <listitem><para>File path parameters may contain non-ascii
        characters and should use the exact same byte values as found in
        the file system directory. Usually, this means that the
        configuration file should use the system default locale
        encoding.</para>
        </listitem>
        <listitem><para>The <envar>unac_except_trans</envar> parameter
        should be encoded in UTF-8. If your system locale is not UTF-8, and
        you need to also specify non-ascii file paths, this poses a
        difficulty because common text editors cannot handle multiple
        encodings in a single file. In this relatively unlikely case, you
        can edit the configuration file as two separate text files with
        appropriate encodings, and concatenate them to create the complete
        configuration.</para>
        </listitem>
      </itemizedlist>
      </para>

	  <sect2 id="RCL.INSTALL.CONFIG.ENVIR">
	  <title>Environment variables</title>

	  <variablelist>
		<varlistentry>
		  <term><varname>RECOLL_CONFDIR</varname></term>
		<listitem><para>Defines the main configuration
		directory.</para></listitem>
		</varlistentry>

		<varlistentry>
		  <term><varname>RECOLL_TMPDIR, TMPDIR</varname></term>
		<listitem><para>Locations for temporary files, in this order
		of priority. The default if none of these is set is to use
		<filename>/tmp</filename>. Big temporary files may be created
		during indexing, mostly for decompressing, and also for
		processing, e.g. email attachments.</para></listitem>
		</varlistentry>

		<varlistentry>
		  <term><varname>RECOLL_CONFTOP, RECOLL_CONFMID</varname></term>
		<listitem><para>Allow adding configuration directories with
		priorities below and above the user directory (see above the
		Configuration overview section for details).</para></listitem>
		</varlistentry>

		<varlistentry>
		  <term><varname>RECOLL_EXTRA_DBS,
		  RECOLL_ACTIVE_EXTRA_DBS</varname></term>
		<listitem><para>
		  Help for setting up external indexes. See <link
		  linkend="RCL.SEARCH.GUI.MULTIDB">this paragraph</link> for
		  explanations.
		</para></listitem>
		</varlistentry>

		<varlistentry>
		  <term><varname>RECOLL_DATADIR</varname></term>
		<listitem><para>Defines replacement for the default location
		of Recoll data files, normally found in, e.g.,
		<filename>/usr/share/recoll</filename>).</para></listitem>
		</varlistentry>

		<varlistentry>
		  <term><varname>RECOLL_FILTERSDIR</varname></term>
		<listitem><para>Defines replacement for the default location
		of Recoll filters, normally found in, e.g.,
		<filename>/usr/share/recoll/filters</filename>).</para></listitem>
		</varlistentry>

		<varlistentry>
		  <term><varname>ASPELL_PROG</varname></term>
		<listitem><para><command>aspell</command> program to use for
		creating the spelling dictionary. The result has to be
		compatible with the <filename>libaspell</filename> which &RCL;
		is using.</para></listitem>
		</varlistentry>

		<varlistentry>
		  <term><varname>VARNAME</varname></term>
		<listitem><para>Blabla</para></listitem>
		</varlistentry>

	  </variablelist>

	  </sect2>

      <sect2 id="RCL.INSTALL.CONFIG.RECOLLCONF">
        <title>The main configuration file, recoll.conf</title>

        <para><filename>recoll.conf</filename> is the main
         configuration file. It defines things like
         what to index (top directories and things to ignore), and the
         default character set to use for document types which do not
         specify it internally.</para>

        <para>The default configuration will index your home
         directory. If this is not appropriate, start
         <command>recoll</command> to create a blank 
         configuration, click <guimenu>Cancel</guimenu>, and edit
         the configuration file before restarting the command. This
         will start the initial indexing, which may take some time.</para>

        <para>Most of the following parameters can be changed from the
        <guilabel>Index Configuration</guilabel> menu in the
        <command>recoll</command> interface. Some can only be set by
        editing the configuration file.</para>

        <sect3 id="RCL.INSTALL.CONFIG.RECOLLCONF.FILES">
          <title>Parameters affecting what documents we index:</title>

        <variablelist>

          <varlistentry id="RCL.INSTALL.CONFIG.RECOLLCONF.TOPDIRS">
            <term><varname>topdirs</varname></term>
            <listitem><para>Specifies the list of directories or files to
            index (recursively for directories). You can use symbolic links
            as elements of this list. See the
            <varname>followLinks</varname> option about following symbolic links
            found under the top elements (not followed by default).</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>skippedNames</varname></term>
            <listitem>
              <para>A space-separated list of wilcard patterns for
               names of files or directories that should be completely
               ignored. The list defined in the default file is: </para>
<programlisting>
skippedNames = #* bin CVS  Cache cache* caughtspam  tmp .thumbnails .svn \
 	       *~ .beagle .git .hg .bzr loop.ps .xsession-errors \
	       .recoll* xapiandb recollrc recoll.conf 
</programlisting>
              <para>The list can be redefined at any sub-directory in the
		indexed area.</para>
              <para>The top-level directories are not affected by this
                list (that is, a directory in <varname>topdirs</varname>
                might match and would still be indexed).</para>
                <para>The list in the default configuration does not
                exclude hidden directories (names beginning with a
                dot), which means that it may index quite a few things
                that you do not want. On the other hand, email user
                agents like <application>thunderbird</application>
                usually store messages in hidden directories, and you
                probably want this indexed. One possible solution is to
                have <filename>.*</filename> in
                <varname>skippedNames</varname>, and add things like
                <filename>~/.thunderbird</filename> or
                <filename>~/.evolution</filename> in
                <varname>topdirs</varname>.</para> 

                <para>Not even the file names are indexed for patterns
                in this list. See the
                <varname>noContentSuffixes</varname> variable for an alternative
                approach which indexes the file names.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>noContentSuffixes</varname></term>
          <listitem><para>This is a list of file name endings (not
          wildcard expressions, nor dot-delimited suffixes). Only the
          names of matching files will be indexed (no attempt at MIME
          type identification, no decompression, no content
          indexing). This can be redefined for
          subdirectories, and edited from the GUI. The default value is:
<programlisting>
noContentSuffixes = .md5 .map \
       .o .lib .dll .a .sys .exe .com \
       .mpp .mpt .vsd \
	   .img .img.gz .img.bz2 .img.xz .image .image.gz .image.bz2 .image.xz \
       .dat .bak .rdf .log.gz .log .db .msf .pid \
       ,v ~ #
</programlisting>
          </para></listitem>
          </varlistentry>

          <varlistentry><term><varname>skippedPaths</varname> and
             <varname>daemSkippedPaths</varname> </term>
            <listitem>
              <para>A space-separated list of patterns for
               <emphasis>paths</emphasis> of files or directories that should be skipped.
               There is no default in the sample configuration file,
               but the code always adds the configuration and database
               directories in there.</para>
              <para><varname>skippedPaths</varname> is used both by
              batch and real time
              indexing. <varname>daemSkippedPaths</varname> can be
              used to specify things that should be indexed at
              startup, but not monitored.</para>
              <para>Example of use for skipping text files only in a
              specific directory:</para>
              <programlisting>
skippedPaths = ~/somedir/*.txt
              </programlisting>
            </listitem>
          </varlistentry>

          <varlistentry id="RCL.INSTALL.CONFIG.RECOLLCONF.SKIPPEDPATHSFNMPATHNAME">
            <term><varname>skippedPathsFnmPathname</varname></term>
                <listitem><para>The values in the
                <varname>*skippedPaths</varname> variables are matched by
                default with <literal>fnmatch(3)</literal>, with the
                FNM_PATHNAME flag. This means that '/'
                characters must be matched explicitely. You can set
                <varname>skippedPathsFnmPathname</varname> to 0 to disable
                the use of FNM_PATHNAME (meaning that /*/dir3 will match
                /dir1/dir2/dir3).</para>

            </listitem>
          </varlistentry>

	  <varlistentry id="RCL.INSTALL.CONFIG.RECOLLCONF.ZIPSKIPPEDNAMES">
	    <term><varname>zipSkippedNames</varname></term>
	    <listitem><para>A space-separated list of patterns for
               names of files or directories that should be ignored
               inside zip archives. This is used directly by the zip
               handler, and has a function similar to skippedNames, but
               works independantly. Can be redefined for filesystem
               subdirectories. For versions up to 1.19, you will need
               to update the Zip handler and install a supplementary
               Python module. The details are
               described <ulink url="https://bitbucket.org/medoc/recoll/wiki/Filtering%20out%20Zip%20archive%20members">on
		  the &RCL; wiki</ulink>.
	    </para></listitem>
	  </varlistentry>

          <varlistentry id="RCL.INSTALL.CONFIG.RECOLLCONF.FOLLOWLINKS">
            <term><varname>followLinks</varname></term>
            <listitem><para>Specifies if the indexer should follow
            symbolic links while walking the file tree. The default is
            to ignore symbolic links to avoid multiple indexing of
            linked files. No effort is made to avoid duplication when
            this option is set to true. This option can be set
            individually for each of the <varname>topdirs</varname>
            members by using sections. It can not be changed below the
            <varname>topdirs</varname> level.</para>
            </listitem> 
          </varlistentry>

          <varlistentry><term><varname>indexedmimetypes</varname></term>
            <listitem><para>&RCL; normally indexes any file which it
            knows how to read. This list lets you restrict the indexed
            MIME types to what you specify. If the variable is
            unspecified or the list empty (the default), all supported
            types are processed. Can be redefined for subdirectories.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>excludedmimetypes</varname></term>
            <listitem><para> This list lets you exclude some MIME types from
            indexing. Can be redefined for subdirectories.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>compressedfilemaxkbs</varname></term>
            <listitem><para>Size limit for compressed (.gz or .bz2)
            files. These need to be decompressed in a temporary
            directory for identification, which can be very wasteful
            if 'uninteresting' big compressed files are present.
            Negative means no limit, 0 means no processing of any
            compressed file. Defaults to -1.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>textfilemaxmbs</varname></term>
            <listitem><para>Maximum size for text files. Very big text
            files are often uninteresting logs. Set to -1 to disable
            (default 20MB).</para>  
            </listitem>
           </varlistentry>

          <varlistentry><term><varname>textfilepagekbs</varname></term>
            <listitem><para>If set to other than -1, text files will be
            indexed as multiple documents of the given page size. This may
            be useful if you do want to index very big text files as it
            will both reduce memory usage at index time and help with
            loading data to the preview window. A size of a few megabytes
            would seem reasonable (default: 1MB).</para>
            </listitem>
           </varlistentry>

          <varlistentry><term><varname>membermaxkbs</varname></term>
            <listitem><para>This defines the maximum size in kilobytes for
            an archive member (zip, tar or rar at the moment). Bigger
            entries will be skipped.</para>
              </listitem>
            </varlistentry>

          <varlistentry><term><varname>indexallfilenames</varname></term>
            <listitem><para>&RCL; indexes file names in a special
            section of the database to allow specific file names
            searches using wild cards. This parameter decides if 
            file name indexing is performed only for files with MIME
            types that would qualify them for full text indexing, or
            for all files inside the selected subtrees, independently of
            MIME type.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>usesystemfilecommand</varname></term>
            <listitem><para>Decide if we execute a system command 
            (<command>file</command> <option>-i</option> by default)
            as a final step for determining the MIME type for a file
            (the main procedure uses suffix associations as defined in
            the <filename>mimemap</filename> file). This can be useful
            for files with suffix-less names, but it will also cause
            the indexing of many bogus "text" files.</para>
            </listitem> 
	  </varlistentry>

          <varlistentry><term><varname>systemfilecommand</varname></term>
            <listitem><para>Command to use for mime for mime type
            determination if <literal>usesystefilecommand</literal> is
            set. Recent versions of <command>xdg-mime</command> sometimes
            work better than <command>file</command>.</para>
            </listitem> 
	  </varlistentry>

          <varlistentry><term><varname>processwebqueue</varname></term>
            <listitem><para>If this is set, process the directory where
            Web browser plugins copy visited pages for indexing.</para>
            </listitem>
           </varlistentry>

          <varlistentry><term><varname>webqueuedir</varname></term>
            <listitem><para>The path to the web indexing queue. This is
            hard-coded in the Firefox plugin as
            <filename>~/.recollweb/ToIndex</filename> so there should be no
            need to change it.</para> 
            </listitem>
           </varlistentry>

        </variablelist>
       </sect3>

       <sect3 id="RCL.INSTALL.CONFIG.RECOLLCONF.TERMS">
	<title>Parameters affecting how we generate terms:</title>

        <para>Changing some of these parameters will imply a full
          reindex. Also, when using multiple indexes, it may not make sense
          to search indexes that don't share the values for these parameters,
          because they usually affect both search and index operations.</para>

        <variablelist>

          <varlistentry><term><varname>indexStripChars</varname></term>
            <listitem><para>Decide if we strip characters of diacritics and
                convert them to lower-case before terms are indexed. If we
                don't, searches sensitive to case and diacritics can be
                performed, but the index will be bigger, and some marginal
                weirdness may sometimes occur. The default is a stripped
                index (<literal>indexStripChars = 1</literal>) for
                now. When using multiple indexes for a search,
                this parameter must be defined identically for
                all. Changing the value implies an index reset.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>maxTermExpand</varname></term>
            <listitem><para>Maximum expansion count for a single term (e.g.:
                when using wildcards). The default of 10000 is reasonable and
                will avoid queries that appear frozen while the engine is
                walking the term list.</para>
            </listitem>
         </varlistentry>

          <varlistentry><term><varname>maxXapianClauses</varname></term>
            <listitem><para>Maximum number of elementary clauses we can add
                to a single Xapian query. In some cases, the result of term
                expansion can be multiplicative, and we want to avoid using
                excessive memory. The default of 100 000 should be both
                high enough in most cases and compatible with current
                typical hardware configurations.</para>
            </listitem>
         </varlistentry>

          <varlistentry><term><varname>nonumbers</varname></term>
            <listitem><para>If this set to true, no terms will be generated
            for numbers. For example "123", "1.5e6", 192.168.1.4, would not
            be indexed ("value123" would still be). Numbers are often quite
            interesting to search for, and this should probably not be set
            except for special situations, ie, scientific documents with huge
            amounts of numbers in them. This can only be set for a whole
            index, not for a subtree.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>nocjk</varname></term>
            <listitem><para>If this set to true, specific east asian
            (Chinese Korean Japanese) characters/word splitting is
            turned off. This will save a small amount of cpu if you
            have no CJK documents. If your document base does include
            such text but you are not interested in searching it,
            setting <varname>nocjk</varname> may be a significant time
            and space saver.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>cjkngramlen</varname></term>
            <listitem><para>This lets you adjust the size of n-grams
            used for indexing CJK text. The default value of 2 is
            probably appropriate in most cases. A value of 3 would
            allow more precision and efficiency on longer words, but
            the index will be approximately twice as large.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>indexstemminglanguages</varname></term>
            <listitem><para>A list of languages for which the stem
            expansion databases will be built. See <citerefentry>
            <refentrytitle>recollindex</refentrytitle>
            <manvolnum>1</manvolnum> </citerefentry> or use the
            <command>recollindex</command> <option>-l</option> command
            for possible values. You can add a stem expansion database
            for a different language by using
            <command>recollindex</command> <option>-s</option>, but it
            will be deleted during the next indexing. Only languages
            listed in the configuration file are permanent.</para>
            </listitem> 
          </varlistentry>
         
          <varlistentry><term><varname>defaultcharset</varname></term>
            <listitem><para>The name of the character set used for
            files that do not contain a character set definition (ie:
            plain text files). This can be redefined for any
            sub-directory. If it is not set at all, the character set
            used is the one defined by the nls environment (
	    <envar>LC_ALL</envar>, <envar>LC_CTYPE</envar>, 
	    <envar>LANG</envar>), or <literal>iso8859-1</literal> 
	    if nothing is set.</para> 
	   </listitem>
         </varlistentry>

          <varlistentry><term><varname>unac_except_trans</varname></term>
            <listitem><para>This is a list of characters, encoded in UTF-8,
            which should be handled specially when converting text to
            unaccented lowercase.  For example, in Swedish, the letter
            <literal>a with diaeresis</literal> has full alphabet
            citizenship and should not be turned into an
            <literal>a</literal>. Each element in the space-separated list
            has the special character as first element and the translation
            following. The handling of both the lowercase and upper-case
            versions of a character should be specified, as appartenance to
            the list will turn-off both standard accent and case
            processing. Example for Swedish:</para>
                <programlisting>
unac_except_trans =  åå Åå ää Ää öö Öö
            </programlisting>

            <para>Note that the translation is not limited to a single
            character, you could very well have something like
            <literal>üue</literal> in the list.</para>

             <para>The default value set for
             <literal>unac_except_trans</literal> can't be listed here
             because I have trouble with SGML and UTF-8, but it only
             contains ligature decompositions: german ss, oe, ae, fi,
             fl.</para>

             <para>This parameter can't be defined for subdirectories, it
             is global, because there is no way to do otherwise when
             querying. If you have document sets which would need different
             values, you will have to index and query them separately.</para> 
              </listitem>
            </varlistentry>

          <varlistentry><term><varname>maildefcharset</varname></term>
            <listitem><para>This can be used to define the default
		character set specifically for email messages which don't
		specify it. This is mainly useful for readpst (libpst) dumps,
		which are utf-8 but do not say so.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>localfields</varname></term>
            <listitem><para>This allows setting fields for all documents
            under a given directory. Typical usage would be to set an
            "rclaptg" field, to be used in <filename>mimeview</filename> to
            select a specific viewer. If several fields are to be set, they
            should be separated with a semi-colon (';') character, which there
            is currently no way to escape. Also note the initial semi-colon. 
            Example:
		<literal>localfields= ;rclaptg=gnus;other = val</literal>, then
		select specifier viewer with
		<literal>mimetype|tag=...</literal> in
		<filename>mimeview</filename>.</para>  
            </listitem>
           </varlistentry>

          <varlistentry><term><varname>testmodifusemtime</varname></term>
            <listitem><para>If true, use mtime instead of default ctime to
              determine if a file has been modified (in addition to
              size, which is always used). Setting this can reduce
              re-indexing on systems where extended attributes are
              modified (by some other application), but not indexed
              (changing extended attributes only affects
              ctime). Notes:
              <itemizedlist>
                <listitem><para>This may prevent detection of change
                in some marginal file rename cases (the target would
                need to have the same size and
                mtime).</para></listitem>
                <listitem><para>You should probably also set
                noxattrfields to 1 in this case, except if you still
                prefer to perform xattr indexing, for example if the
                local file update pattern makes it of value (as in
                general, there is a risk for pure extended attributes
                updates without file modification to go
                undetected).</para></listitem>
              </itemizedlist>
                Perform a full index reset after changing the value of
                this parameter.
            </para></listitem>
          </varlistentry>

          <varlistentry><term><varname>noxattrfields</varname></term>
            <listitem><para>Recoll versions 1.19 and later
                automatically translate file extended attributes into
                document fields (to be processed according to the
                parameters from the <filename>fields</filename>
                file). Setting this variable to 1 will disable the
                behaviour.</para></listitem>
          </varlistentry>

          <varlistentry id="RCL.INSTALL.CONFIG.RECOLLCONF.METADATACMDS">
            <term><varname>metadatacmds</varname></term>
            <listitem><para>This allows executing external commands
                for each file and storing the output in &RCL; document
                fields. This could be used for example to index
                external tag data. The value is a list of field names
                and commands, don't forget an initial
                semi-colon. Example:
                <programlisting>
[/some/area/of/the/fs]
metadatacmds = ; tags = tmsu tags %f; otherfield = somecmd -xx %f
                </programlisting>
              </para> <para>As a specially disgusting hack brought by
                &RCL; 1.19.7, if a "field name" begins
                with <literal>rclmulti</literal>, the data returned by
                the command is expected to contain multiple field
                values, in configuration file format. This allows
                setting several fields by executing a single
                command. Example:
                <programlisting>
metadatacmds = ; rclmulti1 = somecmd %f
                </programlisting>
                If <literal>somecmd</literal> returns data in the form
                of:
                <programlisting>
field1 = value1
field2 = value for field2
                </programlisting>
                <literal>field1</literal>
                and <literal>field2</literal> will be set inside the
                document metadata.</para>
            </listitem>
          </varlistentry>

        </variablelist>


       </sect3>

       <sect3 id="RCL.INSTALL.CONFIG.RECOLLCONF.STORAGE">
	<title>Parameters affecting where and how we store things:</title>

	<variablelist>
          <varlistentry><term><varname>dbdir</varname></term>
            <listitem><para>The name of the Xapian data directory. It
            will be created if needed when the index is
            initialized. If this is not an absolute path, it will be
            interpreted relative to the configuration directory. The
            value can have embedded spaces but starting or trailing
            spaces will be trimmed. You cannot use quotes here.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>idxstatusfile</varname></term>
            <listitem><para>The name of the scratch file where the indexer
                process updates its status. Default:
            <filename>idxstatus.txt</filename> inside the configuration
            directory.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>maxfsoccuppc</varname></term>
            <listitem><para>Maximum file system occupation before we
            stop indexing. The value is a percentage, corresponding to
            what the "Capacity" df output column shows.  The default
            value is 0, meaning no checking. </para>
            </listitem>
          </varlistentry>

	  <varlistentry><term><varname>mboxcachedir</varname></term>
	    <listitem><para>The directory where mbox message offsets cache
	    files are held. This is normally $RECOLL_CONFDIR/mboxcache, but
	    it may be useful to share a directory between different
	    configurations.</para>
	    </listitem>
	  </varlistentry>

	  <varlistentry><term><varname>mboxcacheminmbs</varname></term>
	    <listitem><para>The minimum mbox file size over which we
		cache the offsets. There is really no sense in caching
		offsets for small files. The default is 5 MB.</para>
	    </listitem>
	   </varlistentry>

          <varlistentry><term><varname>webcachedir</varname></term>
            <listitem><para>This is only used by the web browser
            plugin indexing code, and defines where the cache for visited
            pages will live. Default:
            <filename>$RECOLL_CONFDIR/webcache</filename></para> 
            </listitem>

           </varlistentry>
          <varlistentry><term><varname>webcachemaxmbs</varname></term>
            <listitem><para>This is only used by the web browser
            plugin indexing code, and defines the maximum size for the web
            page cache. Default: 40 MB. Quite unfortunately, this is only
            taken into account when creating the cache file. You need to
            delete the file for a change to be taken into account.</para> 
            </listitem>
           </varlistentry>


          <varlistentry><term><varname>idxflushmb</varname></term>
            <listitem><para>Threshold (megabytes of new text data) where we
            flush from memory to disk index. Setting this can help control
            memory usage. A value of 0 means no explicit flushing, letting
            Xapian use its own default, which is flushing every 10000 (or
            XAPIAN_FLUSH_THRESHOLD) documents, which gives little memory
            usage control, as memory usage also depends on average document
            size. The default value is 10, and it is probably a bit low. If
            your system usually has free memory, you can try higher values
            between 20 and 80. In my experience, values beyond 100 are
            always counterproductive.</para> 
            </listitem>
          </varlistentry>

        </variablelist>
       </sect3>

       <sect3 id="RCL.INSTALL.CONFIG.RECOLLCONF.IDXTHREADS">
	<title>Parameters affecting multithread processing</title>

        <para>The &RCL; indexing process 
          <command>recollindex</command> can use multiple threads to
          speed up indexing on multiprocessor systems. The work done
          to index files is divided in several stages and some of the
          stages can be executed by multiple threads. The stages are:
          <orderedlist>
            <listitem>File system walking: this is always performed by
              the main thread.</listitem>
            <listitem>File conversion and data extraction.</listitem>
            <listitem>Text processing (splitting, stemming,
            etc.)</listitem>
            <listitem>&XAP; index update.</listitem>
          </orderedlist>
        </para>
        <para>You can also read a 
          <ulink url="http://www.recoll.org/idxthreads/threadingRecoll.html">
            longer document</ulink> about the transformation of
          &RCL; indexing to multithreading.</para>

        <para>The threads configuration is controlled by two
          configuration file parameters.</para>

	 <variablelist>

          <varlistentry><term><varname>thrQSizes</varname></term>
            <listitem><para>This variable defines the job input queues
                configuration. There are three possible queues for
                stages 2, 3 and 4, and this parameter should give the
                queue depth for each stage (three integer values). If
                a value of -1 is used for a given stage, no queue is
                used, and the thread will go on performing the next
                stage. In practise, deep queues have not been shown to
                increase performance. A value of 0 for the first queue
                tells &RCL; to perform autoconfiguration (no need for
                the two other values in this case) - this is the
                default configuration.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>thrTCounts</varname></term>
            <listitem><para>This defines the number of threads used
                for each stage. If a value of -1 is used for one of
                the queue depths, the corresponding thread count is
                ignored. It makes no sense to use a value other than 1
                for the last stage because updating the &XAP; index is
                necessarily single-threaded (and protected by a
                mutex).</para>
            </listitem>
          </varlistentry>

         </variablelist>

         <para>The following example would use three queues (of depth 2),
         and 4 threads for converting source documents, 2 for
         processing their text, and one to update the index. This was
         tested to be the best configuration on the test system
         (quadri-processor with multiple disks).
<programlisting>
thrQSizes = 2 2 2
thrTCounts =  4 2 1
</programlisting>
         </para>

         <para>The following example would use a single queue, and the
           complete processing for each document would be performed by
           a single thread (several documents will still be processed
           in parallel in most cases). The threads will use mutual
           exclusion when entering the index update stage. In practise
           the performance would be close to the precedent case in
           general, but worse in certain cases (e.g. a Zip archive
           would be performed purely sequentially), so the previous
           approach is preferred. YMMV...  The 2 last values for
           thrTCounts are ignored.
<programlisting>
thrQSizes = 2 -1 -1
thrTCounts =  6 1 1
</programlisting>
         </para>

         <para>The following example would disable
           multithreading. Indexing will be performed by a single
           thread.
<programlisting>
thrQSizes = -1 -1 -1
</programlisting>
         </para>

       </sect3>

       <sect3 id="RCL.INSTALL.CONFIG.RECOLLCONF.MISC">
	<title>Miscellaneous parameters:</title>

	 <variablelist>

           <varlistentry><term><varname>autodiacsens</varname></term>
            <listitem><para>IF the index is not stripped, decide if we
                automatically trigger diacritics sensitivity if the search
                term has accented characters (not in
                <literal>unac_except_trans</literal>). Else you need to use
                the query language and the <literal>D</literal> modifier to
                specify diacritics sensitivity. Default is no.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>autocasesens</varname></term>
            <listitem><para>IF the index is not stripped, decide if we
                automatically trigger character case sensitivity if the
                search term has upper-case characters in any but the first
                position. Else you need to use the query language and the
                <literal>C</literal> modifier to specify character-case
                sensitivity. Default is yes.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>loglevel,daemloglevel</varname></term>
            <listitem><para>Verbosity level for recoll and
            recollindex. A value of 4 lists quite a lot of
            debug/information messages. 2 only lists errors. The
            <literal>daem</literal>version is specific to the indexing monitor
            daemon.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>logfilename,
		daemlogfilename</varname></term> 
            <listitem><para>Where the messages should go. 'stderr' can
            be used as a special value, and is the default. The
            <literal>daem</literal>version is specific to the indexing monitor
            daemon.</para>
            </listitem>
          </varlistentry>

           <varlistentry><term><varname>checkneedretryindexscript</varname></term>
           <listitem><para>This defines the name for a command
           executed by <command>recollindex</command> when starting
           indexing. If the exit status of the command is 0,
           <command>recollindex</command> retries to index all files
           which previously could not be indexed because of data
           extraction errors. The default value is a script which
           checks if any of the common <filename>bin</filename>
           directories have changed (indicating that a helper program
           may have been installed).</para>
           </listitem>
           </varlistentry>

          <varlistentry><term><varname>mondelaypatterns</varname></term>
            <listitem><para>This allows specify wildcard path patterns
            (processed with fnmatch(3) with 0 flag), to match files which
            change too often and for which a delay should be observed before
            re-indexing. This is a space-separated list, each entry being a
            pattern and a time in seconds, separated by a colon. You can
            use double quotes if a path entry contains white
            space. Example:</para>  
              <programlisting>
mondelaypatterns = *.log:20 "this one has spaces*:10"
              </programlisting>
            </listitem>
           </varlistentry>

          <varlistentry><term><varname>monixinterval</varname></term>
            <listitem><para>Minimum interval (seconds) for processing the
            indexing queue. The real time monitor does not process each
            event when it comes in, but will wait this time for the queue
            to accumulate to diminish overhead and in order to aggregate
            multiple events to the same file. Default 30 S.</para>
            </listitem>
           </varlistentry>

          <varlistentry><term><varname>monauxinterval</varname></term>
            <listitem><para>Period (in seconds) at which the real time
            monitor will regenerate the auxiliary databases (spelling,
            stemming) if needed. The default is one hour.</para>
              </listitem>
           </varlistentry>

            <varlistentry><term><varname>monioniceclass, monioniceclassdata
             </varname></term><listitem><para>These allow defining the
             <application>ionice</application> class and data used by the
             indexer (default class 3, no data).</para>
              </listitem>
            </varlistentry>

            <varlistentry><term><varname>filtermaxseconds</varname></term>
              <listitem><para>Maximum handler execution time, after which it
            is aborted. Some postscript programs just loop...</para> 
              </listitem>
            </varlistentry>
          <varlistentry><term><varname>filtersdir</varname></term>
            <listitem><para>A directory to search for the external
            input handler scripts used to index some types of files. The
            value should not be changed, except if you want to modify
            one of the default scripts. The value can be redefined for
            any sub-directory. </para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>iconsdir</varname></term>
            <listitem><para>The name of the directory where
            <command>recoll</command> result list icons are
            stored. You can change this if you want different
            images.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>idxabsmlen</varname></term>
            <listitem><para>&RCL; stores an abstract for each indexed
            file inside the database. The text can come from an actual
            'abstract' section in the document or will just be the
            beginning of the document. It is stored in the index so
            that it can be displayed inside the result lists without
            decoding the original
            file. The <varname>idxabsmlen</varname> parameter defines
            the size of the stored abstract. The default value is 250 bytes.
            The search interface gives you the choice to display this
            stored text or a synthetic abstract built by extracting
            text around the search terms. If you always
            prefer the synthetic abstract, you can reduce this value
            and save a little space.
            </para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>idxmetastoredlen</varname></term>
            <listitem><para>Maximum stored length for metadata
                fields. This does not affect indexing (the whole field is
                processed anyway), just the amount of data stored in the
                index for the purpose of displaying fields inside result
                lists or previews. The default value is 150 bytes which
                may be too low if you have custom fields.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>aspellLanguage</varname></term>
            <listitem><para>Language definitions to use when creating
            the aspell dictionary.  The value must match a set of
            aspell language definition files. You can type "aspell
            config" to see where these are installed (look for
            data-dir). The default if the variable is not set is to
            use your desktop national language environment to guess
            the value.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>noaspell</varname></term>
            <listitem><para>If this is set, the aspell dictionary
            generation is turned off. Useful for cases where you don't
            need the functionality or when it is unusable because
            aspell crashes during dictionary generation.</para>
            </listitem>
          </varlistentry>

          <varlistentry><term><varname>mhmboxquirks</varname></term>
            <listitem><para>This allows definining location-related quirks
            for the mailbox handler. Currently only the
            <literal>tbird</literal> flag is defined, and it should be set
            for directories which hold
            <application>Thunderbird</application> data, as their folder
            format is weird.</para>
              </listitem>
            </varlistentry>


        </variablelist>
       </sect3>
      </sect2>

      <sect2 id="RCL.INSTALL.CONFIG.FIELDS">
	<title>The fields file</title>

	<para>This file contains information about dynamic fields handling
	in &RCL;. Some very basic fields have hard-wired behaviour,
	and, mostly, you should not change the original data inside the
	<filename>fields</filename> file. But you can create custom fields
	fitting your data and handle them just like they were native
	ones.</para>

	<para>The <filename>fields</filename> file has several sections,
	which each define an aspect of fields processing. Quite often,
	you'll have to modify several sections to obtain the desired
	behaviour.</para>

	<para>We will only give a short description here, you should refer
	to the comments inside the default file for more detailed
	information.</para>

	<para>Field names should be lowercase alphabetic ASCII.</para>

        <variablelist>

          <varlistentry>
            <term>[prefixes]</term>
            <listitem><para>A field becomes indexed (searchable) by having
            a prefix defined in this section.</para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>[stored]</term>
            <listitem><para>A field becomes stored (displayable inside
            results) by having its name listed in this section (typically
            with an empty value).</para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>[aliases]</term>
            <listitem><para>This section defines lists of synonyms for the
            canonical names used inside the <literal>[prefixes]</literal>
            and <literal>[stored]</literal> sections</para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>[queryaliases]</term>
            <listitem><para>This section also defines aliases for the
            canonic field names, with the difference that the substitution
            will only be used at query time, avoiding any possibility that
            the value would pick-up random metadata from documents.</para>
            </listitem>
          </varlistentry>
          <varlistentry>
            <term>handler-specific sections</term>
            <listitem><para>Some input handlers may need specific
            configuration for handling fields. Only the email message handler
            currently has such a section (named
            <literal>[mail]</literal>). It allows indexing arbitrary email
            headers in addition to the ones indexed by default. Other such
            sections may appear in the future.</para>
            </listitem>
          </varlistentry>

	</variablelist>

      <para>Here follows a small example of a personal
      <filename>fields</filename> 
      file. This would extract a specific email header and
      use it as a searchable field, with data displayable inside result
      lists. (Side note: as the email handler does no decoding on the values,
      only plain ascii headers can be indexed, and only the
      first occurrence will be used for headers that occur several times).

<programlisting>[prefixes]
# Index mailmytag contents (with the given prefix)
mailmytag = XMTAG

[stored]
# Store mailmytag inside the document data record (so that it can be
# displayed - as %(mailmytag) - in result lists).
mailmytag = 

[queryaliases]
filename = fn
containerfilename = cfn

[mail]
# Extract the X-My-Tag mail header, and use it internally with the
# mailmytag field name
x-my-tag = mailmytag
</programlisting>
</para>


      <sect3 id="RCL.INSTALL.CONFIG.FIELDS.XATTR">
	<title>Extended attributes in the fields file</title>

        <para>&RCL; versions 1.19 and later process user extended
        file attributes as documents fields by default.</para>

        <para>Attributes are processed as fields of the same name,
          after removing the <literal>user</literal> prefix on
          Linux.</para>

        <para>The <literal>[xattrtofields]</literal>
          section of the <filename>fields</filename> file allows
          specifying translations from extended attributes names to
          &RCL; field names. An empty translation disables use of the
          corresponding attribute data.</para>

      </sect3>

      </sect2>

      <sect2 id="RCL.INSTALL.CONFIG.MIMEMAP">
        <title>The mimemap file</title>

        <para><filename>mimemap</filename> specifies the
        file name extension to MIME type mappings.</para> 

        <para>For file names without an extension, or with an unknown
        one, the system's <command>file</command> <option>-i</option> 
	command will be
        executed to determine the MIME type (this can be switched off
        inside the main configuration file).</para>

        <para>The mappings can be specified on a per-subtree basis,
        which may be useful in some cases. Example:
        <application>gaim</application> logs have a
        <filename>.txt</filename> extension but 
        should be handled specially, which is possible because they
        are usually all located in one place.</para>

        <para>The <varname>recoll_noindex</varname>
        <filename>mimemap</filename> variable has been moved to
        <filename>recoll.conf</filename> and renamed to
        <varname>noContentSuffixes</varname>, while keeping the same
        function, as of &RCL; version 1.21. For older &RCL; versions,
        see the documentation for <varname>noContentSuffixes</varname>
        but use <varname>recoll_noindex</varname> in
        <filename>mimemap</filename>.</para>

      </sect2>

      <sect2 id="RCL.INSTALL.CONFIG.MIMECONF">
        <title>The mimeconf file</title>

        <para><filename>mimeconf</filename> specifies how the
         different MIME types are handled for indexing, and which icons
         are displayed in the <command>recoll</command> result lists.</para>

        <para>Changing the parameters in the [index] section is
         probably not a good idea except if you are a &RCL;
         developer.</para> 

        <para>The [icons] section allows you to change the icons which
         are displayed by <command>recoll</command> in the result
         lists (the values are the basenames of the png images inside
         the <filename>iconsdir</filename> directory (specified in
         <filename>recoll.conf</filename>).</para>

      </sect2>

      <sect2 id="RCL.INSTALL.CONFIG.MIMEVIEW">
        <title>The mimeview file</title>

        <para><filename>mimeview</filename> specifies which programs
          are started when you click on an <guilabel>Open</guilabel> link
          in a result list. Ie: HTML is normally displayed using
         <application>firefox</application>, but you may prefer
         <application>Konqueror</application>, your
         <application>openoffice.org</application> 
         program might be named <command>oofice</command> instead of
         <command>openoffice</command> etc.</para>

        <para>Changes to this file can be done by direct editing, or
        through the <command>recoll</command> GUI preferences dialog.</para>

        <para>If <guilabel>Use desktop preferences to choose document
        editor</guilabel> is checked in the &RCL; GUI preferences, all
        <filename>mimeview</filename> entries will be ignored except the
        one labelled <literal>application/x-all</literal> (which is set to
        use <command>xdg-open</command> by default).</para>

        <para>In this case, the <literal>xallexcepts</literal> top level
          variable defines a list of MIME type exceptions which
          will be processed according to the local entries instead of being
          passed to the desktop. This is so that specific &RCL; options
          such as a page number or a search string can be passed to
          applications that support them, such as the
          <application>evince</application> viewer.</para>

        <para>As for the other configuration files, the normal usage
          is to have a <filename>mimeview</filename> inside your own
          configuration directory, with just the non-default entries,
          which will override those from the central configuration
          file.</para>

        <para>All viewer definition entries must be placed under a
          <literal>[view]</literal> section.</para>

	<para>The keys in the file are normally MIME types. You can add an
	  application tag to specialize the choice for an area of the
	  filesystem (using a <varname>localfields</varname> specification
	  in <filename>mimeconf</filename>). The syntax for the key is 
<replaceable>mimetype</replaceable><literal>|</literal><replaceable>tag</replaceable></para>

        <para>The <varname>nouncompforviewmts</varname> entry, (placed at
        the top level, outside of the <literal>[view]</literal> section),
        holds a list of MIME types that should not be uncompressed before
        starting the viewer (if they are found compressed, ie:
        <replaceable>mydoc.doc.gz</replaceable>).</para>

        <para>The right side of each assignment holds a command to be
        executed for opening the file. The following substitutions are
        performed:</para> 

        <itemizedlist>
          <listitem>
            <formalpara><title>%D</title>
              <para>Document date</para></formalpara>
          </listitem> 

          <listitem><formalpara><title>%f</title>
              <para>File name. This may be the name of a temporary file if
              it was  necessary to create one (ie: to extract a subdocument
              from a  container).</para></formalpara>
          </listitem>

          <listitem><formalpara><title>%i</title>
              <para>Internal path, for subdocuments of containers. The
              format depends on the container type. If this appears in the
              command line, &RCL; will not create a temporary file to
              extract the subdocument, expecting the called application
              (possibly a script) to be able to handle it.</para></formalpara>
          </listitem>

          <listitem><formalpara><title>%M</title>
              <para>MIME type</para></formalpara> 
          </listitem>

          <listitem><formalpara><title>%p</title>
              <para>Page index. Only significant for a subset of document
              types, currently only PDF, Postscript and DVI files. Can be
              used to start the editor at the right page for a match or
              snippet.</para></formalpara>
          </listitem>

          <listitem><formalpara><title>%s</title>
              <para>Search term. The value will only be set for documents
              with indexed page numbers (ie: PDF). The value will be one of
              the matched search terms. It would allow pre-setting the
              value in the "Find" entry inside Evince for example, for easy
              highlighting of the term.</para></formalpara>  
          </listitem>

          <listitem><formalpara><title>%u</title>
              <para>Url.</para></formalpara> 
          </listitem>
        </itemizedlist>

        <para>In addition to the predefined values above, all strings like
        <literal>%(fieldname)</literal> will be replaced by the value of
        the field named <literal>fieldname</literal> for the
        document. This could be used in combination with field
        customisation to help with opening the document.</para> 

      </sect2>

      <sect2 id="RCL.INSTALL.CONFIG.PTRANS">
        <title>The <filename>ptrans</filename> file</title>

        <para><filename>ptrans</filename> specifies query-time path
          translations. These can be useful
          in <link linkend="RCL.SEARCH.PTRANS">multiple
          cases</link>.</para>
        <para>The file has a section for any index which needs
          translations, either the main one or additional query
          indexes. The sections are named with the &XAP; index
          directory names. No slash character should exist at the end
          of the paths (all comparisons are textual). An exemple
          should make things sufficiently clear</para>

        <programlisting>
          [/home/me/.recoll/xapiandb]
          /this/directory/moved = /to/this/place

          [/path/to/additional/xapiandb]
          /server/volume1/docdir = /net/server/volume1/docdir
          /server/volume2/docdir = /net/server/volume2/docdir
        </programlisting>

      </sect2>


      <sect2 id="RCL.INSTALL.CONFIG.EXAMPLES">
        <title>Examples of configuration adjustments</title>

        <sect3 id="RCL.INSTALL.CONFIG.EXAMPLES.ADDVIEW">
          <title>Adding an external viewer for an non-indexed type</title>

          <para>Imagine that you have some kind of file which does not
            have indexable content, but for which you would like to have a
            functional <guilabel>Open</guilabel> link in the result list
            (when found by file name). The file names end in
            <replaceable>.blob</replaceable> and can be displayed by
            application <replaceable>blobviewer</replaceable>.</para>

          <para>You need two entries in the configuration files for this
	    to work:</para>

          <itemizedlist>
            <listitem><para>In <filename>$RECOLL_CONFDIR/mimemap</filename>
		(typically <filename>~/.recoll/mimemap</filename>), add the
		following line:<programlisting>
.blob = application/x-blobapp
</programlisting>
		Note that the MIME type is made up here, and you could
		call it <replaceable>diesel/oil</replaceable> just the
		same.</para>
            </listitem>
            <listitem><para>In <filename>$RECOLL_CONFDIR/mimeview</filename>
		under the <literal>[view]</literal> section, add:</para>
              <programlisting>
application/x-blobapp = blobviewer %f
</programlisting>
              <para>We are supposing
              that <replaceable>blobviewer</replaceable> wants a file
              name parameter here, you would use <literal>%u</literal> if
              it liked URLs better.</para>
            </listitem>
          </itemizedlist>

          <para>If you just wanted to change the application used by
            &RCL; to display a MIME type which it already knows, you
            would just need to edit <filename>mimeview</filename>. The
            entries you add in your personal file override those in the
            central configuration, which you do not need to
            alter. <filename>mimeview</filename> can also be modified
            from the Gui.</para>

        </sect3>

        <sect3 id="RCL.INSTALL.CONFIG.EXAMPLES.ADDINDEX">
          <title>Adding indexing support for a new file type</title>

          <para>Let us now imagine that the above
            <replaceable>.blob</replaceable> files actually contain
            indexable text and that you know how to extract it with a
            command line program. Getting &RCL; to index the files is
            easy. You need to perform the above alteration, and also to
            add data to the <filename>mimeconf</filename> file
            (typically in <filename>~/.recoll/mimeconf</filename>):</para>
          <itemizedlist>
            <listitem><para>Under the <literal>[index]</literal>
		section, add the following line (more about the
		<replaceable>rclblob</replaceable> indexing script
		later):<programlisting>
application/x-blobapp = exec rclblob
</programlisting></para>
            </listitem>
            <listitem><para>Under the <literal>[icons]</literal>
		section, you should choose an icon to be displayed for the
		files inside the result lists. Icons are normally 64x64
		pixels PNG files which live in
		<filename>/usr/[local/]share/recoll/images</filename>.</para>
            </listitem>
            <listitem><para>Under the <literal>[categories]</literal>
		section, you should add the MIME type where it makes sense
		(you can also create a category). Categories may be used
		for filtering in advanced search.</para>
            </listitem>
          </itemizedlist>

          <para>The <replaceable>rclblob</replaceable> handler should
            be an executable program or script which exists inside
            <filename>/usr/[local/]share/recoll/filters</filename>. It
            will be given a file name as argument and should output the
            text or html contents on the standard output.</para>

          <para>The <link linkend="RCL.PROGRAM.FILTERS">filter
              programming</link> section describes in more detail how
              to write an input handler.</para> 

        </sect3>

      </sect2>

    </sect1>

  </chapter>

</book>

