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.
Recoll indexing options are set inside text configuration files located in a configuration directory. There can be several such directories, each of which define the parameters for one index.
The configuration files can be edited by hand or through the Indexing configuration dialog (Preferences 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.
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.
For each index, there are two sets of configuration files. System-wide configuration files are kept in a directory named like /usr/[local/]share/recoll/examples, and define default values, shared by all indexes. For each index, a parallel set of files defines the customized parameters.
The default location of the configuration is the .recoll directory in your home. Most people will only use this directory.
This location can be changed, or others can be added with the RECOLL_CONFDIR environment variable or the -c option parameter to recoll and recollindex.
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 indexing. recollindex will proceed immediately. To avoid mistakes, the automatic directory creation will only occur for the default location, not if -c or RECOLL_CONFDIR were used (in the latter cases, you will have to create the directory).
All configuration files share the same format. For example, 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 definitions 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.
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.
White space is used for separation inside lists. List elements with embedded spaces can be quoted using double-quotes.
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, start recoll to create a blank configuration, click Cancel, and edit the configuration file before restarting the command. This will start the initial indexing, which may take some time.
Paramers:
Specifies the list of directories or files to index (recursively for directories). The indexer will not follow symbolic links inside the indexed trees by default (see the followLinks options though).
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.
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:
skippedNames = #* bin CVS Cache cache* caughtspam tmp .thumbnails .svn \ *~ recollrc
The list can be redefined for sub-directories, 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.
Not even the file names are indexed for patterns in this list. See the recoll_noindex variable in mimemap for an alternative approach which indexes the file names.
A space-separated list of patterns for paths 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.
skippedPaths is used both by batch and real time indexing. daemSkippedPaths can be used to specify things that should be indexed at startup, but not monitored.
Example of use for skipping text files only in a specific directory:
skippedPaths = ~/somedir/∗.txt
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 topdirs members by using sections. It can not be changed below the topdirs level.
Verbosity level for recoll and recollindex. A value of 4 lists quite a lot of debug/information messages. 2 only lists errors. The daemversion is specific to the indexing monitor daemon.
Where the messages should go. 'stderr' can be used as a special value, and is the default. The daemversion is specific to the indexing monitor daemon.
A list of languages for which the stem expansion databases will be built. See recollindex(1) or use the recollindex -l command 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 indexing. Only languages listed in the configuration file are permanent.
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 (LC_ALL, LC_CTYPE, LANG), or iso8859-1 if nothing is set.
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.
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 documents (memory usage depends on average document size). The default value is 10.
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 sub-directory.
The name of the directory where recoll result list icons are stored. You can change this if you want different images.
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.
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 suffix-less names, but it will also cause the indexing of many bogus "text" files.
Recoll 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.
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.
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 indexing, or for all files inside the selected subtrees, independently of mime type.
Recoll 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 idxabsmlen 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.
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.
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.
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 nocjk may be a significant time and space saver.
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.
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).
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 (which avoids unnecessary decompressions or file executions). This is partially redundant with skippedNames in the main configuration file, with a few differences: it will not affect directories, it cannot be made dependant on the file-system location (it is a configuration-wide parameter), and the file names will still be indexed (not even the file names are indexed for patterns in skippedNames. recoll_noindex is used mostly for things known to be unindexable by a given Recoll version. Having it there avoids cluttering the more user-oriented and locally customized skippedNames.
mimeconf specifies how the different mime types are handled for indexing, and which icons are displayed in the recoll result lists.
Changing the parameters in the [index] section is probably not a good idea except if you are a Recoll developer.
The [icons] section allows you to 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).
mimeview specifies which programs are started when you click on an Edit link in a result list. Ie: HTML is normally displayed using firefox, but you may prefer Konqueror, your openoffice.org program might be named oofice instead of openoffice etc.
Changes to this file can be done by direct editing, or through the recoll user preferences dialog.
As for the other configuration files, the normal usage is to have a mimeview inside your own configuration directory, with just the non-default entries, which will override those from the central configuration file.
Please note that these entries must be placed under a [view] section.
If Use desktop preferences to choose document editor is checked in the user preferences, all mimeview entries will be ignored except the one labelled application/x-all (which is set to use xdg-open by default).
Imagine that you have some kind of file which does not have indexable content, but for which you would like to have a functional Edit link in the result list (when found by file name). The file names end in .blob and can be displayed by application blobviewer.
You need two entries in the configuration files for this to work:
In $RECOLL_CONFDIR/mimemap (typically ~/.recoll/mimemap), add the following line:
application/x-blobapp = .blob
Note that the mime type is made up here, and you could call it diesel/oil just the same.
In $RECOLL_CONFDIR/mimeview under the [view] section:
application/x-blobapp = blobviewer %f
We are supposing that blobviewer wants a file name parameter here, you would use %u if it liked URLs better.
If you just wanted to change the application used by Recoll to display a mime type which it already knows, you would just need to edit mimeview. The entries you add in your personal file override those in the central configuration, which you do not need to alter
Let us now imagine that the above .blob files actually contain indexable text and that you know how to extract it with a command line program. Getting Recoll to index the files is easy. You need to perform the above alteration, and also to add data to the mimeconf file (typically in ~/.recoll/mimeconf):
Under the [index] section, add the following line (more about the rclblob indexing script later):
application/x-blobapp = exec rclblob
Under the [icons] 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 /usr/[local/]share/recoll/images.
Under the [categories] 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.
The rclblob filter should be an executable program or script which exists inside /usr/[local/]share/recoll/filters. It will be given a file name as argument and should output the text contents on the standard output.
The filter programming section describes in more detail how to write a filter.