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                           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.

     --------------------------------------------------------------

   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

     --------------------------------------------------------------

                        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).

     --------------------------------------------------------------

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 internet
   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.

     --------------------------------------------------------------

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. (Actually, there is a way to reconstruct
   a document from the information in the database, but the result is
   not nice, as all formatting, punctuation and capitalisation are
   lost).

   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 currently 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 default configuration is copied into a
   standard location (usually something like
   /usr/[local/]share/recoll/examples) during installation. The
   default parameters from this file may be overriden by values that
   you set inside your personal configuration, found by default in
   the .recoll subdirectory of your home directory. The default
   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.

     --------------------------------------------------------------

                         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.

   +----------------------------------------------------------------+
   | Side note: there is nothing in Recoll and Xapian that would    |
   | prevent interfacing with a real time file modification         |
   | monitor, but this would tend to consume significant system     |
   | resources for dubious gain, because you rarely need a full     |
   | text search to find documents you just modified. recollindex   |
   | -i can be used to add individual files to the index if you     |
   | want to play with this, see the manual page.                   |
   +----------------------------------------------------------------+

   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.

     --------------------------------------------------------------

2.2. The indexation configuration

   Values set in the system-wide configuration file (named like
   /usr/[local/]share/recoll/examples/recoll.conf) can be overriden
   by those set in the personal one, 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 central one. If you want to adjust the
   configuration before indexation, just click Cancel when the
   program asks if it should start initial indexation. This will have
   created a .recoll directory containing empty configuration files.

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

     --------------------------------------------------------------

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.

     --------------------------------------------------------------

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.

     --------------------------------------------------------------

                           Chapter 3. Search

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

     --------------------------------------------------------------

3.1. Simple search

    1. Start the recoll program.

    2. Possibly choose a search mode: Any term or All terms or File
       name.

    3. Enter search term(s) in the text field at the top of the
       window.

    4. Click the Search button or hit the Enter key to start the
       search.

   The initial default search mode is Any term. This will look for
   documents with any of the search terms (the ones with more terms
   will get better scores). All terms will ensure that only documents
   with all the terms will be returned. File name will specifically
   look for file names, and allows using wildcards (*, ? , []).

   You can 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 the Preview link
   for an entry will open an internal preview window for the
   document. Clicking the Edit link will attempt to start an external
   viewer (have a look at the mimeconf configuration 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.

   The Preview and Edit edit links may not be present for all
   entries, meaning that Recoll has no configured way to preview a
   given file type (which was indexed by name only), or no configured
   external viewer for the file type. This can sometimes be adjusted
   simply by tweaking the mimemap and mimeconf configuration files.

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

     --------------------------------------------------------------

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, none of the given words, or a given file name
   (with wildcard expansion). All relevant fields will 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.

   Click on the Show query details link at the top of the result page
   to see the query expansion.

     --------------------------------------------------------------

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.

     --------------------------------------------------------------

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. An activated sort is indicated in the
   result list header.

     --------------------------------------------------------------

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.

   File names. All file name elements (the broken up file path) are
   entered as terms during indexation, and you can specify them as
   ordinary terms in normal search fields. Alternatively, you can use
   specific file name search which will only look for file names and
   can use wildcard expansion.

   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).

     --------------------------------------------------------------

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, dealing with the interface
   itself, and with the parameters used for searching and returning
   results.

   User interface parameters:

     * Number of results in a result page

     * Result list font: There is quite a lot of information shown in
       the result list, and you may want to customise the font and/or
       font size. The rest of the fonts used by Recoll are determined
       by your generic QT config (try the qtconfig command.

     * Html help browser: this will let you chose your the preferred
       browser which will be started from the Help menu to read the
       user manual. You can enter a simple name if the command is in
       your PATH, or browse for a full pathname.

     * Show document type icons in result list: icons in the result
       list can be turned off. They take quite a lot of space and
       convey relatively little useful information.

   Search parameters:

     * Stemming language: 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 main 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.

     * Dynamically build abstracts: this decides if Recoll tries to
       build document abstracts when displaying the result list.
       Abstracts are constructed by taking context from the document
       information, around the search terms. This can slow down
       result list display significantly for big documents, and you
       may want to turn it off.

     * Replace abstracts from documents: this decides if we should
       synthetize and display an abstract in place of an explicit
       abstract found within the document itself.

     --------------------------------------------------------------

                        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 development currently
   uses version 3.3.5, but any 3.3 version is probably ok).

   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 (these are run-time dependencies. None is
   needed for building Recoll):

     * PDF: pdftotext is part of the Xpdf package.

     * Postscript: pstotext.

     * MS Word: antiword.

     * RTF: unrtf

     * dvi: dvips

     * djvu: DjVuLibre

     * MP3: Recoll will use the id3info command from the id3lib
       package to extract tag information. Without it, only the
       filenames will be indexed.

   Text, Html, mail folders and Openoffice files are processed
   internally.

     --------------------------------------------------------------

  4.1.2. Building

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

   Depending on the qt configuration on your system, you may have to
   set the QTDIR and QMAKESPECS variables in your environment:

     * QTDIR should point to the directory above the one that holds
       the qt include files (ie: qt.h).

     * QMAKESPECS should be set to the name of one of the qt mkspecs
       subdirectories (ie: linux-g++).

   On many Linux systems, QTDIR is set by the login scripts, and
   QMAKESPECS is not needed because there is a default link in
   mkspecs/.

   The Recoll configure script does a better job of checking these
   variables after release 1.1.1. Before this, unexplained errors
   will occur during compilation if the environment is not set up.
   Also, for 1.1.0 the qmake command should be in your PATH (later
   releases can also find it in $QTDIR/bin).

   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).

     --------------------------------------------------------------

  4.1.3. Installation

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

   You can then proceed to configuration.

     --------------------------------------------------------------

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.

     --------------------------------------------------------------

  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.

     --------------------------------------------------------------

4.3. Configuration overview

   There are two sets of configuration files. The system-wide files
   are kept in a directory named like
   /usr/[local/]share/recoll/examples, they define default values for
   the system. A parallel set of files exists in the .recoll
   directory in your home (this can be changed with the
   RECOLL_CONFDIR environment variable. The database is also kept in
   .recoll by default, (this can be changed by a configuration
   parameter).

   If the .recoll directory does not exist when recoll or recollindex
   are started, it will be created with a set of empty configuration
   files. 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 default 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.

     --------------------------------------------------------------

  4.3.1. Main configuration file

   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.

           The top-level directories are not affected by this list
           (that is, a directory in topdirs might match and would
           still be indexed).

           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, mail user agents like thunderbird
           usually store messages in hidden directories, and you
           probably want this indexed. One possible solution is to
           have .* in skippedNames, and add things like
           ~/.thunderbird or ~/.evolution in topdirs.

   loglevel

           Verbosity level for recoll and recollindex. A value of 4
           lists quite a lot of debug/information messages. 2 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. If it is not
           set at all, the character set used is the one defined by
           the nls environment (LC_ALL, LC_CTYPE, LANG), or iso8859-1
           if nothing is set.

   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.

   indexallfilenames

           Recoll 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 indexation, or for all files
           inside the selected subtrees, independant of mime type.

     --------------------------------------------------------------

  4.3.2. The mimemap file

   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.

   mimemap also has a recoll_noindex variable which is a list of
   suffixes. Matching files will be skipped (avoids unnecessary
   decompressions or file executions). This is partially redundant
   with skippedNames in the main configuration file, with two
   differences: it will not affect directories, and it can be changed
   for any subdirectory.

     --------------------------------------------------------------

  4.3.3. The mimeconf file

   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, your openoffice.org program might be named
   oofice instead of openoffice ...). 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).

     --------------------------------------------------------------