Open Source Projects Europe

More documentation can be found in the doc/ directory or at http://www.recoll.org


                               Recoll user manual

  Jean-Francois Dockes

   <jean-francois.dockes@wanadoo.fr>

   Copyright (c) 2005 Jean-Francois Dockes

   This document introduces full text search notions and describes the
   installation and use of the Recoll application.

   [ Split HTML / Single HTML ]

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   Table of Contents

   1. Introduction

                1.1. Giving it a try

                1.2. Full text search

                1.3. Recoll overview

   2. Indexation

                2.1. Introduction

                2.2. The indexation configuration

                2.3. Starting indexation

                2.4. Using cron to automate indexation

   3. Search

                3.1. Simple search

                3.2. Complex/advanced search

                3.3. Document history

                3.4. Result list sorting

                3.5. Search tips, shortcuts

                3.6. Customising the search interface

   4. Installation

                4.1. Building from source

                             4.1.1. Prerequisites

                             4.1.2. Building

                             4.1.3. Installation

                4.2. Installing a prebuilt copy

                             4.2.1. Installing through a package system

                             4.2.2. Installing a prebuilt Recoll

                4.3. Configuration overview

                             4.3.1. Main configuration file

                             4.3.2. The mimemap file

                             4.3.3. The mimeconf file

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                            Chapter 1. Introduction

1.1. Giving it a try

   If you do not like reading manuals (who does?) and would like to give
   Recoll a try, just perform installation and start the recoll user
   interface, which will index your home directory and let you search it
   right after.

   Do not do this if your home has a huge number of documents and you do not
   want to wait or are very short on disk space. In this case, you may want
   to edit the configuration file first to restrict the indexed area.

   Also be aware that you will need to install the appropriate supporting
   applications for document types that need them (for example antiword for
   ms-word files), and that the default character set used to read raw text
   files for indexing is iso8859-1, which may not be appropriate for you.

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1.2. Full text search

   Recoll is a full text search application. Full text search applications
   let you find your data by content rather than by external attributes (like
   a file name). More specifically, they will let you specify words (terms)
   that should or should not appear in the text you are looking for, and
   return a list of matching documents, ordered so that the most relevant
   documents will appear first.

   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 those terms are prominent.

   This mode of operation has been made very familiar by www search engines.

   The notion of relevance is a difficult one, as only you, the user,
   actually know which documents are relevant to your search, and the
   application can only try a guess. The quality of this guess is probably
   the most important element for a search application.

   In many cases, you are looking for all the forms of a word, not for a
   specific form or spelling. These different forms may include plurals,
   different tenses for a verb, or terms derived from the same root or stem
   (exemple: floor, floors, floored, floorings...). Recoll will by default
   expand queries to all such related terms (words that reduce to the same
   stem). This expansion can be disabled at search time.

   Stemming, by itself, does not provide for misspellings or phonetic
   searches. Recoll currently does not support these.

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1.3. Recoll overview

   Recoll uses the Xapian information retrieval library as its storage and
   retrieval engine. Xapian is a very mature package using a sophisticated
   probabilistic ranking model. Recoll provides the interface to get data
   into (indexation) and out (searching) of the system.

   In practice, Xapian works by remembering where terms appear in your
   document files. The acquisition process is called indexation.

   The resulting database can be big (roughly the size of the original
   document set), but it is not a document archive. Recoll can only display
   documents that still exist at the place from which they were indexed.

   Recoll stores all internal data in Unicode UTF-8 format, and it can index
   files with different character sets, encodings, and languages into the
   same database. It has input filters for many document types.

   Stemming depends on the document language. Recoll stores the unstemmed
   versions of terms and uses auxiliary databases for term expansion. It can
   switch stemming languages, or add a language, without reindexing. Storing
   documents in different languages in the same database is possible, and
   useful in practice, but does introduce possibilities of confusion. Recoll
   makes no attempt at automatic language recognition.

   Recoll has many parameters which define exactly what to index, and how to
   classify and decode the source documents. These are kept in a
   configuration file. A sample configuration is installed into the .recoll
   subdirectory of your home directory when you first execute a Recoll
   command. The initial configuration will index your home directory with
   default parameters and should be sufficient for giving Recoll a try, but
   you may want to adjust it later.

   Indexation is started automatically the first time you execute the recoll
   search graphical user interface, or by executing the recollindex command.

   Searches are performed inside the recoll program, which has many options
   to help you find what you are looking for.

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                             Chapter 2. Indexation

2.1. Introduction

   Indexation is the process by which the set of documents is analyzed and
   the data entered into the database. Recoll indexation is normally
   incremental: documents will only be processed if they have been modified.
   On the first execution, of course, all documents will need processing. A
   full index build can be forced later on by specifying an option to the
   indexation command (recollindex -z).

   Recoll indexation takes place at discrete times. There is currently no
   interface to real time file modification monitors. The typical usage is to
   have a nightly indexation run programmed into your cron file.

   Recoll knows about quite a few different document types. The parameters
   for document types recognition and processing are set in configuration
   files Most file types, like HTML or word processing files, only hold one
   document. Some file types, like mail folder files can hold many
   individually indexed documents.

   Recoll indexation processes plain text, HTML, openoffice and e-mail files
   internally. Other types (ie: postscript, pdf, ms-word, rtf) need external
   applications for preprocessing. The list is in the installation section.

   Without further configuration, Recoll will index all appropriate files
   from your home directory, with a reasonable set of defaults, if you live
   in western Europe or the USA. If your normal character set is not
   iso8859-1, you almost certainly need to adjust the configuration.

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2.2. The indexation configuration

   The main configuration file is named $HOME/.recoll/recoll.conf by default
   or $RECOLL_CONFDIR/recoll.conf if RECOLL_CONFDIR is set.

   The most accurate documentation for editing the file is given by comments
   inside the default file that will be created when you first start recoll.
   If you want to adjust the configuration before indexation, just click
   Cancel when the program asks if it should start initial indexation.

   The configuration is also documented inside the installation chapter of
   this document, or in the recoll.conf(5) man page.

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2.3. Starting indexation

   Indexation is performed either by the recollindex program, or by the
   indexation thread inside the recoll program (use the File menu).

   If the recoll program finds no database when it starts, it will
   automatically start indexation (except if cancelled).

   It is best to avoid interrupting the indexation process, as this may
   sometimes leave the database in a bad state. This is not a serious
   problem, as you then just need to clear everything and restart the
   indexation: the database files are normally stored in the
   $HOME/.recoll/xapiandb directory, which you can just delete if needed.
   Alternatively, you can start recollindex -z, which will reset the database
   before indexation.

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2.4. Using cron to automate indexation

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

 30 3 * * * recollindex > /tmp/recolltrace 2>&1

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

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                               Chapter 3. Search

   The recoll program provides the user interface for searching. It is based
   on the QT library.

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3.1. Simple search

   Start the recoll program, then enter search term(s) in the text field at
   the top left of the window. Clicking the Search button or hitting the
   Enter key will start a search. By default, this will look for documents
   with any of the terms (the ones with more terms will get better scores).
   You can check the All terms checkbox to ensure that only documents with
   all the terms will be returned. Use the Tools / Advanced search dialog for
   more complex searches.

   After starting a search, a list of results will instantly be displayed in
   the main list window. Clicking on an entry will open an internal preview
   window for the document. Double-clicking will attempt to start an external
   viewer (have a look at the ~/.recoll/mimeconf file to see how these are
   configured).

   By default, the document list is presented in order of relevance (how well
   the system estimates that the document matches the query). You can specify
   a different ordering by using the Tools / Sort parameters dialog.

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3.2. Complex/advanced search

   The advanced search dialog has fields that will allow a more refined
   search, looking for documents with all given words, a given exact phrase,
   or none of the given words (all fields may be combined by an implicit AND
   clause).

   It will let you search for documents of specific mime types (ie: only
   text/plain, or text/html or application/pdf etc...)

   It will let you restrict the search results to a subtree of the indexed
   area.

   Click on the Start Search button in the advanced search dialog to start
   the search. The button in the main window always performs a simple search.

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3.3. Document history

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

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3.4. Result list sorting

   The documents in a result list are normally sorted in order of relevance.
   It is possible to specify different sort parameters by using the Sort
   parameters dialog (located in the Tools menu).

   The tool sorts a specified number of the most relevant documents in the
   result list, according to specified criteria. The currently available
   criteria are date and mime type.

   The sort parameters stay in effect until they are explicitely reset, or
   the program exits.

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3.5. Search tips, shortcuts

   Disabling stem expansion. Entering a capitalized word in any search field
   will prevent stem expansion (no search for gardening if you enter Garden
   instead of garden). This is the only case where character case should make
   a difference for a Recoll search.

   Phrases. A phrase can be looked for by enclosing it in double quotes.
   Example: "user manual" will look only for occurrences of user immediately
   followed by manual. You can use the This exact phrase field of the
   advanced search dialog to the same effect.

   Query explanation. 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.

   Quitting. Entering ^Q almost anywhere will close the application.

   Closing previews. Entering ^W in a preview tab will close it (and, for the
   last tab, close the preview window).

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3.6. Customising the search interface

   It is possible to customise some aspects of the search interface by using
   Query configuration entry in the Preferences menu.

   There are two tabs in the dialog, to modify the appearance of the user
   interface (result list appearance), or the parameters used for searching
   (language used for stem expansion).

   The stemming language can be chosen among those that were specified in the
   configuration file, or later added with recollindex -s (See the
   recollindex manual). Stemming languages which are dynamically added will
   be deleted at the next indexation pass unless they are also added in the
   configuration file.

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                            Chapter 4. Installation

4.1. Building from source

  4.1.1. Prerequisites

   At the very least, you will need to download and install the xapian core
   package (Recoll currently uses version 0.9.2), and the qt runtime and
   development packages (Recoll currently uses version 3.3.3).

   You will most probably be able to find a binary package for qt for your
   system. You may have to compile Xapian, but this is not difficult (if you
   are using FreeBSD, there is a port).

   You may also need libiconv. Recoll currently uses version 1.9 (this should
   not be critical). On Linux systems, the iconv interface is part of libc
   and you should not need to do anything special.

   External file types. Recoll uses external applications to index some file
   types. You need to install them for the file types that you wish to have
   indexed:

     * MS Word: antiword.

     * PDF: pdftotext is part of the Xpdf package.

     * Postscript: pstotext.

     * RTF: unrtf

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  4.1.2. Building

   Recoll has been built on Linux (redhat7.3, mandriva 2005), FreeBSD and
   Solaris 8. If you build on another system, I would very much welcome
   patches.

   Normal procedure:

         cd recoll-xxx
         configure
         make
         (practises usual hardship-repelling invocations)
     

   There little autoconfiguration. The configure script will mainly link one
   of the system-specific files in the mk directory to mk/sysconf. 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 uname -s).

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  4.1.3. Installation

   Either type make install or execute recollinstall targetdir, in the root
   of the source tree. This will copy the commands to $targetdir/bin and the
   sample configuration files, scripts and other shared data to
   $targetdir/share/recoll.

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4.2. Installing a prebuilt copy

  4.2.1. Installing through a package system

   If you are lucky enough to be using a port system or a prebuilt package
   (RPM or other), just follow the usual procedure, and have a look at the
   configuration section.

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  4.2.2. Installing a prebuilt Recoll

   The unpackaged binary versions are just compressed tar files of a build
   tree, where only the useful parts were kept (executables and sample
   configuration).

   The executable binary files are built with a static link to libxapian and
   libiconv, to make installation easier (no dependencies). However, this
   also means that you cannot change the versions which are used.

   After extracting the tar file, you can proceed with installation as if you
   had built the package from source.

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4.3. Configuration overview

   The personal configuration files and the database are normally kept in the
   .recoll directory in your home (this can be changed with the
   RECOLL_CONFDIR environment variable, and a parameter inside the main
   configuration file). If this directory does not exist when recoll or
   recollindex are started, the directory will be created and the sample
   configuration files will be copied. recoll will give you a chance to edit
   the configuration file before starting indexation. recollindex will
   proceed immediately.

   Most of the parameters specific to the recoll GUI are set through the
   Preferences menu and stored in the standard QT place ($HOME/.qt/recollrc).
   You probably do not want to edit this by hand.

   For other options, Recoll uses text configuration files. You will have to
   edit them by hand for now (there is still some hope for a GUI
   configuration tool in the future). The most accurate documentation for the
   configuration parameters is given by comments inside the sample files, and
   we will just give a general overview here.

   All configuration files share the same format. For exemple, a short
   extract of the main configuration file might look as follows:

         # Space-separated list of directories to index.
         topdirs =  ~/docs /usr/share/doc

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

   There are three kinds of lines:

     * Comment (starts with #) or empty.

     * Parameter affectation (name = value).

     * Section definition ([somedirname]).

   Section lines allow redefining some parameters for a directory subtree.
   Some of the parameters used for indexation are looked up hierarchically
   from the more to the less specific. Not all parameters can be meaningfully
   redefined, this is specified for each in the next section.

   The tilde character (~) is expanded in file names to the name of the
   user's home directory.

   White space is used for separation inside lists. Elements with embedded
   spaces can be quoted using double-quotes.

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  4.3.1. Main configuration file

   ~/.recoll/recoll.conf 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.

   The default configuration will index your home directory. If this is not
   appropriate, use recoll to copy the sample configuration, click Cancel,
   and edit the configuration file before restarting the command. This will
   start the initial indexation, which may take some time.

   Paramers:

   topdirs

           Specifies the list of directories to index (recursively).

   skippedNames

           A space-separated list of patterns for names of files or
           directories that should be completely ignored. The list defined in
           the default file is:

 *~ #* bin CVS  Cache caughtspam  tmp

           The list can be redefined for subdirectories, but is only actually
           changed for the top level ones in topdirs

   loglevel

           Verbosity level for recoll and recollindex. A value of 4 lists
           quite a lot of debug/information messages. 3 only lists errors.

   logfilename

           Where should the messages go. 'stderr' can be used as a special
           value.

   filtersdir

           A directory to search for the external filter 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 subdirectory.

   indexstemminglanguages

           A list of languages for which the stem expansion databases will be
           built. See recollindex(1) for possible values. You can add a stem
           expansion database for a different language by using recollindex
           -s, but it will be deleted during the next indexation. Only
           languages listed in the configuration file are permanent.

   iconsdir

           The name of the directory where recoll result list icons are
           stored. You can change this if you want different images.

   dbdir

           The name of the Xapian database directory. It will be created if
           needed when the database is initialized.

   defaultcharset

           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 subdirectory.

   guesscharset

           Decide if we try to guess the character set of files if no
           internal value is available (ie: for plain text files). This does
           not work well in general, and should probably not be used.

   usesystemfilecommand

           Decide if we use the file -i system command as a final step for
           determining the mime type for a file (the main procedure uses
           suffix associations as defined in the mimemap file). This can be
           useful for files with suffixless names, but it will also cause the
           indexation of many bogus "text" files.

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  4.3.2. The mimemap file

   ~/.recoll/mimemap specifies the file name extension to mime type mappings.

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

   mimemap also has a list of extensions which should be ignored totally (to
   avoid losing time by executing file for things that certainly should not
   be indexed).

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

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  4.3.3. The mimeconf file

   ~/.recoll/mimeconf specifies how the different mime types are handled for
   indexation, and for display.

   Changing the indexation parameters is probably not a good idea except if
   you are a Recoll developper.

   You may want to adjust the external viewers defined in (ie: html is either
   previewed internally or displayed using firefox, but you may prefer
   mozilla...). Look for the [view] section.

   You can also change the icons which are displayed by recoll in the result
   lists (the values are the basenames of the png images inside the iconsdir
   directory (specified in recoll.conf).

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