Section: Po4a Tools (1p)
Updated: 2022-07-14
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po4a - update both the PO files and translated documents in one shot  


po4a [options] config_file  


po4a (PO for anything) eases the maintenance of documentation translation using the classical gettext tools. The main feature of po4a is that it decouples the translation of content from its document structure. Please refer to the page po4a(7) for a gentle introduction to this project.

When you run the po4a program for the first time, with only a configuration file and the documents to translate (called master documents), it produces a POT file (also called translation template) that contains all of the translatable strings in the document in a form that eases the work of translators.

Those POT files can either be translated with a specific editor such as the GNOME Translation Editor, KDE's Lokalize or poedit, or they can be integrated in an online localization platform such as weblate or pootle. The translation result is a set of PO files, one per language.

When you run the po4a program with both the master documents and the PO files, it produces the translated documents by injecting the content's translation (found in the PO files) into the structure of the original master document.

If the master documents changed in the meanwhile, po4a will update the PO and POT files accordingly, so that the translators can easily detect the modifications and update their work. Depending on your settings, po4a will discard the partially translated documents, or produce a document mixing English (for the new or modified paragraphs) and the target language (for paragraphs where translation is already in the PO file).

By default, the translated documents are produced when at least 80% of their content is translated (see the --keep option below). Discarding translations as soon as they are not 100% may be discouraging for the translators, while showing ``translations'' that are too incomplete may be troubling for the end users.  

Graphical overview

 master documents ---+---->-------->---------+
  (doc authoring)    |                       |
                     V   (po4a executions)   >-----+--> translations
                     |                       |     |
 existing PO files -->--> updated PO files >-+     |
      ^                            |               |
      |                            V               |
      +----------<---------<-------+               ^
       (manual translation process)                |
 addendum -->--------------------------------------+

The master documents are authored by the documentation writers. Any changes are automatically reflected by po4a in the PO files, that are then updated by the translators. All changes to the PO files (either manual or by po4a) are automatically reflected in translated documents. You can mimic this behavior using the po4a-updatepo(1) and po4a-translate(1) scripts in makefiles, but this quickly becomes bothersome and repetitive (see po4a(7)). It is highly recommended to use the po4a program in your build process.  


-k, --keep
Minimal threshold for translation percentage to keep (i.e. write) the resulting file (default: 80). I.e. by default, files have to be translated at least at 80% to be written on disk.
-h, --help
Show a short help message.
-M, --master-charset
Charset of the files containing the documents to translate. Note that all master documents must use the same charset.
-L, --localized-charset
Charset of the files containing the localized documents. Note that all translated documents will use the same charset.
-A, --addendum-charset
Charset of the addenda. Note that all the addenda should be in the same charset.
-V, --version
Display the version of the script and exit.
-v, --verbose
Increase the verbosity of the program.
-q, --quiet
Decrease the verbosity of the program.
-d, --debug
Output some debugging information.
-o, --option
Extra option(s) to pass to the format plugin. See the documentation of each plugin for more information about the valid options and their meanings. For example, you could pass '-o tablecells' to the AsciiDoc parser, while the text parser would accept '-o tabs=split'.
-f, --force
Always generate the POT and PO files, even if po4a considers it is not necessary.

The default behavior (when --force is not specified) is the following:

If the POT file already exists, it is regenerated if a master document or the configuration file is more recent (unless --no-update is provided). The POT file is also written in a temporary document and po4a verifies that the changes are really needed.

Also, a translation is regenerated only if its master document, the PO file, one of its addenda or the configuration file is more recent. To avoid trying to regenerate translations which do not pass the threshold test (see --keep), a file with the .po4a-stamp extension can be created (see --stamp).

If a master document includes files, you should use the --force flag because the modification time of these included files are not taken into account.

The PO files are always re-generated based on the POT with msgmerge -U.

Tells po4a to create stamp files when a translation is not generated because it does not reach the threshold. These stamp files are named according to the expected translated document, with the .po4a-stamp extension.

Note: This only activates the creation of the .po4a-stamp files. The stamp files are always used if they exist, and they are removed with --rm-translations or when the file is finally translated.

Do not generate the translated documents, only update the POT and PO files.
Do not change the POT and PO files, only the translation may be updated.
Keeps the existing translation files even if the translation doesn't meet the threshold specified by --keep. This option does not create new translation files with few content, but it will save existing translations which decay because of changes to the master files.

WARNING: This flag changes the po4a behavior in a rather drastic way: your translated files will not get updated at all until the translation improves. Only use this flag if you prefer shipping an outdated translated documentation rather than only shipping an accurate untranslated documentation.

Remove the translated files (implies --no-translations).
This flag does nothing since 0.41, and may be removed in later releases.
This flag does nothing since 0.41, and may be removed in later releases.
--translate-only translated-file
Translate only the specified file. It may be useful to speed up processing if a configuration file contains a lot of files. Note that this option does not update PO and POT files. This option can be used multiple times.
--variable var=value
Define a variable that will be expanded in the po4a configuration file. Every occurrence of $(var) will be replaced by value. This option can be used multiple times.
--srcdir SRCDIR
Set the base directory for all input documents specified in the po4a configuration file.

If both destdir and srcdir are specified, input files are searched in the following directories, in order: destdir, the current directory and srcdir. Output files are written to destdir if specified, or to the current directory.

--destdir DESTDIR
Set the base directory for all the output documents specified in the po4a configuration file (see --srcdir above).

Options modifying the POT header

--porefs type
Specify the reference format. Argument type can be one of never to not produce any reference, file to only specify the file without the line number, counter to replace line number by an increasing counter, and full to include complete references (default: full).
--wrap-po no|newlines|number (default: 76)
Specify how the po file should be wrapped. This gives the choice between either files that are nicely wrapped but could lead to git conflicts, or files that are easier to handle automatically, but harder to read for humans.

Historically, the gettext suite has reformatted the po files at the 77th column for cosmetics. This option specifies the behavior of po4a. If set to a numerical value, po4a will wrap the po file after this column and after newlines in the content. If set to newlines, po4a will only split the msgid and msgstr after newlines in the content. If set to no, po4a will not wrap the po file at all. The reference comments are always wrapped by the gettext tools that we use internally.

Note that this option has no impact on how the msgid and msgstr are wrapped, i.e. on how newlines are added to the content of these strings.

Language of the source files containing the documents to translate. Note that all master documents must use the same language.
--msgid-bugs-address email@address
Set the report address for msgid bugs. By default, the created POT files have no Report-Msgid-Bugs-To fields.
--copyright-holder string
Set the copyright holder in the POT header. The default value is ``Free Software Foundation, Inc.''
--package-name string
Set the package name for the POT header. The default is ``PACKAGE''.
--package-version string
Set the package version for the POT header. The default is ``VERSION''.

Options to modify the PO files

--msgmerge-opt options
Extra options for msgmerge(1).

Note: $lang will be extended to the current language.

This option removes --previous from the options passed to msgmerge. This is necessary to support versions of gettext earlier than 0.16.
This option adds --previous to the options passed to msgmerge. It requires gettext 0.16 or later, and is activated by default.


po4a expects a configuration file as argument. This file must contain the following elements:
The path to the PO files and the list of languages existing in the project;
Optionally, some global options and so-called configuration aliases that are used as templates to configure individual master files;
The list of each master file to translate, along with specific parameters.

All lines contain a command between square braces, followed by its parameters. Comments begin with the char '#' and run until the end of the line. You can escape the end of line to spread a command over several lines.

Some full examples are presented on this page, while other examples can be found in the "t/cfg" directory of the source distribution.  

Finding the PO and POT files

The simplest solution is to explicitly give the path to POT and PO files, as follows:

 [po4a_paths] man/po/project.pot de:man/po/de.po fr:man/po/fr.po

This specifies the path to the POT file first, and then the paths to the German and French PO files.

The same information can be written as follows to reduce the risk of copy/paste errors:

 [po4a_langs] fr de
 [po4a_paths] man/po/project.pot $lang:man/po/$lang.po

The $lang component is automatically expanded using the provided languages list, reducing the risk of copy/paste error when a new language is added.

You can further compact the same information by only providing the path to the directory containing your translation project, as follows.

 [po_directory] man/po/

The provided directory must contain a set of PO files, each named XX.po with "XX" the ISO 639-1 of the language used in this file. The directory must also contain a single POT file, with the ".pot" file extension. For the first run, this file can be empty but it must exist (po4a cannot guess the name to use before the extension).

Note that you must choose only one between "po_directory" and "po4a_paths". The first one ("po_directory") is more compact, further reduces the risk of copy/paste error, but forces you to use the expected project structure and file names. The second one ("po4a_paths"), is more explicit, probably more readable, and advised when you setup your first project with po4a.

Centralized or split PO files?

By default, po4a produces one single PO file per target language, containing the whole content of your translation project. As your project grows, the size of these files may become problematic. When using weblate, it is possible to specify priorities for each translation segment (i.e., msgid) so that the important ones get translated first. Still, some translation teams prefer to split the content in several files.

To have one PO file per master file, you simply have to use the string $master in the name of your PO files on the "[po4a_paths]" line, as follows.

 [po4a_paths] doc/$master/$master.pot $lang:doc/$master/$lang.po

With this line, po4a will produce separate POT and PO files for each document to translate. For example, if you have 3 documents and 5 languages, this will result in 3 POT files and 15 PO files. These files are named as specified on the "po4a_paths" template, with $master substituted to the basename of each document to translate. In case of name conflict, you can specify the POT file to use as follows, with the "pot=" parameter. This feature can also be used to group several translated files into the same POT file.

 [po4a_langs] de fr ja
 [po4a_paths] l10n/po/$master.pot $lang:l10n/po/$master.$lang.po
 [type: xml] foo/gui.xml $lang:foo/gui.$lang.xml pot=foo-gui
 [type: xml] bar/gui.xml $lang:bar/gui.$lang.xml pot=bar
 [type: xml] bar/cli.xml $lang:bar/cli.$lang.xml pot=bar

In split mode, po4a builds a temporary compendium during the PO update, to share the translations between all the PO files. If two PO files have different translations for the same string, po4a will mark this string as fuzzy and will submit both translations in all the PO files containing this string. When unfuzzied by the translator, the translation is automatically used in every PO files.  

Specifying the documents to translate

You must also list the documents that should be translated. For each master file, you must specify the format parser to use, the location of the translated document to produce, and optionally some configuration. Here is an example:

 [type: sgml] doc/my_stuff.sgml fr:doc/fr/mon_truc.sgml \
 [type: man] script fr:doc/fr/script.1 de:doc/de/script.1
 [type: docbook] doc/script.xml fr:doc/fr/script.xml \

But again, these complex lines are difficult to read and modify, e.g. when adding a new language. It is much simpler to reorganize things using the $lang template as follows:

 [type: sgml]    doc/my_stuff.sgml $lang:doc/$lang/my_stuff.sgml
 [type: man]     script.1          $lang:po/$lang/script.1
 [type: docbook] doc/script.xml    $lang:doc/$lang/script.xml


Specifying options

There is two types of options: po4a options are default values to the po4a command line options while format options are used to change the behavior of the format parsers. As a po4a options, you could for example specify in your configuration file that the default value of the --keep command line parameter is 50% instead of 80%. Format options are documented on the specific page of each parsing module, e.g. Locale::Po4a::Xml(3pm). You could for example pass nostrip to the XML parser to not strip the spaces around the extracted strings.

You can pass these options for a specific master file, or even for a specific translation of that file, using "opt:" and "opt_XX:" for the "XX" language. In the following example, the nostrip option is passed to the XML parser (for all languages), while the threshold will be reduced to 0% for the French translation (that is thus always kept).

 [type:xml] toto.xml $lang:toto.$lang.xml opt:"-o nostrip" opt_fr:"--keep 0"

In any case, these configuration chunks must be located at the end of the line. The declaration of files must come first, then the addendum if any (see below), and then only the options. The grouping of configuration chunks is not very important, since elements are internally concatenated as strings. The following examples are all equivalent:

  [type:xml] toto.xml $lang:toto.$lang.xml opt:"--keep 20" opt:"-o nostrip" opt_fr:"--keep 0"
  [type:xml] toto.xml $lang:toto.$lang.xml opt:"--keep 20 -o nostrip" opt_fr:"--keep 0"
  [type:xml] toto.xml $lang:toto.$lang.xml opt:--keep opt:20 opt:-o opt:nostrip opt_fr:--keep opt_fr:0

Note that language specific options are not used when building the POT file. It is for example impossible to pass nostrip to the parser only when building the French translation, because the same POT file is used to update every languages. So the only options that can be language-specific are the ones that are used when producing the translation, as the "--keep" option.

Configuration aliases

To pass the same options to several files, the best is to define a type alias as follows. In the next example, "--keep 0" is passed to every Italian translation using this "test" type, that is an extension of the "man" type.

  [po4a_alias:test] man opt_it:"--keep 0"
  [type: test] man/page.1 $lang:man/$lang/page.1

You can also extend an existing type reusing the same name for the alias as follows. This is not interpreted as as an erroneous recursive definition.

  [po4a_alias:man] man opt_it:"--keep 0"
  [type: man] man/page.1 $lang:man/$lang/page.1

Global default options

You can also use "[options]" lines to define options that must be used for all files, regardless of their type.

  [options] --keep 20 --option nostrip

As with the command line options, you can abbreviate the parameters passed in the configuration file:

  [options] -k 20 -o nostrip

Option priorities

The options of every sources are concatenated, ensuring that the default values can easily be overridden by more specific options. The order is as follows:

"[options]" lines provide default values that can be overridden by any other source.
Type aliases are then used. Language specific settings override the ones applicable to all languages.
Settings that are specific to a given master file override both the default ones and the ones coming from the type alias. In this case also, language specific settings override the global ones.
Finally, parameters provided on the po4a command line override any settings from the configuration file.


Here is an example showing how to quote the spaces and quotes:

 [po_directory] man/po/
 [options] --master-charset UTF-8
 [po4a_alias:man] man opt:"-o \"mdoc=NAME,SEE ALSO\""
 [type:man] t-05-config/test02_man.1 $lang:tmp/test02_man.$lang.1 \
            opt:"-k 75" opt_it:"-L UTF-8" opt_fr:--verbose


Addendum: Adding extra content in the translation

If you want to add an extra section to the translation, for example to give credit to the translator, then you need to define an addendum to the line defining your master file. Please refer to the page po4a(7) for more details on the syntax of addendum files.

 [type: pod] script fr:doc/fr/script.1 \

You can also use language templates as follow:

 [type: pod] script $lang:doc/$lang/script.1 \

If an addendum fails to apply, the translation is discarded.

Modifiers for the addendum declaration

Addendum modifiers can simplify the configuration file in the case where not all languages provide an addendum, or when the list of addenda changes from one language to the other. The modifier is a single char located before the file name.

Include addendum_path if this file does exist, otherwise do nothing.
addendum_path is not a regular addendum but a file containing a list of addenda, one by line. Each addendum may be preceded by modifiers.
addendum_path is discarded, it is not loaded and will not be loaded by any further addendum specification.

The following includes an addendum in any language, but if only it exists. No error is reported if the addendum does not exist.

 [type: pod] script $lang:doc/$lang/script.1  add_$lang:?doc/l10n/script.$lang.add

The following includes a list of addendum for every language:

 [type: pod] script $lang:doc/$lang/script.1  add_$lang:@doc/l10n/script.$lang.add


Filtering the translated strings

Sometimes, you want to hide some strings from the translation process. To that extend, you can give a "pot_in" parameter to your master file to specify the name of the file to use instead of the real master when building the POT file. Here is an example:

  [type:docbook] book.xml          \
          pot_in:book-filtered.xml \

With this setting, the strings to translate will be extracted from the book-filtered.xml (that must be produced before calling po4a) while the translated files will be built from book.xml. As a result, any string that is part of book.xml but not in book-filtered.xml will not be included in the PO files, preventing the translators from providing a translation for them. So these strings will be left unmodified when producing the translated documents. This naturally decreases the level of translation, so you may need the "--keep" option to ensure that the document is produced anyway.  


TODO: Is this section really useful?

Let's assume you maintain a program named foo which has a man page man/foo.1 which naturally is maintained in English only. Now you as the upstream or downstream maintainer want to create and maintain the translation. First you need to create the POT file necessary to send to translators using po4a-gettextize(1).

So for our case we would call

 cd man && po4a-gettextize -f man -m foo.1 -p foo.pot

You would then send this file to the appropriate language lists or offer it for download somewhere on your website.

Now let's assume you received three translations before your next release: de.po (including an addendum de.add), sv.po and pt.po. Since you don't want to change your Makefile(s) whenever a new translation arrives you can use po4a with an appropriate configuration file in your Makefile. Let's call it po4a.cfg. In our example it would look like the following:

 [po_directory] man/po4a/po/

 [type: man] man/foo.1 $lang:man/translated/$lang/foo.1 \
            add_$lang:?man/po4a/add_$lang/$lang.add opt:"-k 80"

In this example we assume that your generated man pages (and all PO and addenda files) should be stored in man/translated/$lang/ (respectively in man/po4a/po/ and man/po4a/add_$lang/) below the current directory. In our example the man/po4a/po/ directory would include de.po, pt.po and sv.po, and the man/po4a/add_de/ directory would include de.add.

Note the use of the modifier ? as only the German translation (de.po) is accompanied by an addendum.

To actually build the translated man pages you would then (once!) add the following line in the build target of the appropriate Makefile:

        po4a po4a.cfg

Once this is set up you don't need to touch the Makefile when a new translation arrives, i.e. if the French team sends you fr.po and fr.add then you simply drop them respectively in man/po4a/po/ and man/po4a/add_fr/ and the next time the program is built the French translation is automatically build as well in man/translated/fr/.

Note that you still need an appropriate target to install localized manual pages with English ones.

Finally if you do not store generated files into your version control system, you will need a line in your clean target as well:
        -rm -rf man/translated  


po4a-gettextize(1), po4a-normalize(1), po4a-translate(1), po4a-updatepo(1), po4a(7).  


 Denis Barbier <barbier@linuxfr.org>
 Nicolas Francois <nicolas.francois@centraliens.net>
 Martin Quinson (mquinson#debian.org)



Copyright 2002-2020 by SPI, inc.

This program is free software; you may redistribute it and/or modify it under the terms of GPL (see the COPYING file).



Graphical overview
Options modifying the POT header
Options to modify the PO files
Finding the PO and POT files
Specifying the documents to translate
Specifying options
Addendum: Adding extra content in the translation
Filtering the translated strings

This document was created by using the manual pages.
Time: 13:09:09 GMT, July 14, 2022
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