Ubuntu Manpage: po4a - update both the PO files and translated documents in one shot

NAME

       po4a - update both the PO files and translated documents in one shot

SYNOPSIS

       po4a [options] config_file

DESCRIPTION

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.

Upon execution, po4a parses all documentation files specified in its configuration file.
It updates the PO files (containing the translation) to reflect any change to the
documentation, and produce a translated documentation by injecting the content's
translation (found in the PO files) into the structure of the original master document.

At first, the PO files only contain the strings to translate from the original
documentation. This file format allows the translators to manually provide a translation
for each paragraph extracted by po4a. If the documentation is modified after translation,
po4a marks the corresponding translations as "fuzzy" in the PO file to request a manual
review by the translators. The translators can also provide so-called "addendum", that are
extra content stating for example who did the translation and how to report bugs.

The workflow of po4a is asynchronous, as suited to open-source projects. The documentation
writers author the master documents at their own pace. The translators review and update
the translations in the PO files. The maintainers rerun po4a on need, to reflect any
change to the original documentation to the PO files, and to produce updated documentation
translations, by injecting the latest translation into the latest document structure.

By default, a given translated document is produced when at least 80% of its content is
translated. The untranslated text is kept in the original language. The produced
documentation thus mixes languages if the translation is not complete. You can change the
80% threshold with the --keep option described below. Note however that discarding
translations as soon as they are not 100% may be discouraging for the translators whose
work will almost never be shown to the users, while showing "translations" that are too
incomplete may be troubling for the end users.

Storing the translated documentation files in the version control system is probably a bad
idea, since they are automatically generated. The precious files are the PO files, that
contain the hard work of your fellow translators. Also, some people find it easier to
interact with the translators through an online platform such as weblate, but this is
naturally fully optional.

Quick start tutorial
Let's assume you maintain a program named foo which has a man page man/foo.1 written in
English (the bridge language in most open-source projects, but po4a can be used from or to
any language). Some times ago, someone provided a German translation named man/foo.de.1
and disappeared. This is a problem because you just got a bug report saying that your
documentation contains a gravely misleading information that must be fixed in all
languages, but you don't speak German so you can only modify the original, not the
translation. Now, another contributor wants to contribute a translation to Japanese, a
language that you don't master either.

It is time to convert your documentation to po4a to solve your documentation maintenance
nightmares. You want to update the doc when needed, you want to ease the work of your
fellow translators, and you want to ensure that your users never see any outdated and thus
misleading documentation.

The conversion includes two steps: setup the po4a infrastructure, and convert the previous
German translation to salvage the previous work. This latter part is done using
po4a-gettextize, as follows. As detailed in the documentation of po4a-gettextize(1), this
process rarely fully automatic, but once it's done, the de.po file containing the German
translation can be integrated in your po4a workflow.

po4a-gettextize --format man --master foo.1 --localized foo.de.1 --po de.po

Let's now configure po4a. With the appropriate file layout, your configuration file could
be as simple as this:

[po_directory] man/po4a/

[type: man] man/foo.1 $lang:man/translated/foo.$lang.1

It specifies that all PO files (containing the work of the translators) are the man/po4a/
directory, and that you have only one master file, man/foo.1. If you had several master
files, you would have several lines similar to the second one. Each such line also specify
where to write the corresponding translation files. Here, the German translation of
man/foo.1 is in man/translated/foo.de.1.

The last thing we need to complete the configuration of po4a is a POT file containing the
template material that should be used to start a new translation. Simply create an empty
file with the .pot extension in the specified po_directory (e.g. man/po4a/foo.pot), and
po4a will fill it with the expected content.

Here is a recap of the files in this setup:

├── man/
│ ├── foo.1 <- The original man page, in English.
│ ├── po4a/
│ │ ├── de.po <- The German PO translation, from gettextization.
│ │ └── foo.pot <- The POT template of future translations (empty at first)
│ └── translated/ <- Directory where the translations will be created
└── po4a.cfg <- The configuration file.

Once setup, executing po4a will parse your documentation, update the POT template file,
use it to update the PO translation files, and use them to update the documentation
translation files. All in one command:

po4a --verbose po4a.cfg

This it. po4a is now fully configured. Once you've fixed your error in man/foo.1, the
offending paragraph in the German translation will be replaced by the fixed text in
English. Mixing languages is not optimal, but it's the only way to remove errors in
translations that you don't even understand, and ensure that the content presented to the
users is never misleading. Updating the German translation is also much easier in the
corresponding PO file, so the language mix-up may not last long. Finally, when the
Japanese translator gives you a jp.po translated file, just drop it in man/po4a/po/. A
translated page will appear as man/translated/foo.jp.1 (provided that enough content is
translated) when you run po4a again.

OPTIONS

-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.

--stamp
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.

--no-translations
Do not generate the translated documents, only update the POT and PO files.

--no-update
Do not change the POT and PO files, only the translation may be updated.

--keep-translations
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.

--rm-translations
Remove the translated files (implies --no-translations).

--no-backups
This flag does nothing since 0.41, and may be removed in later releases.

--rm-backups
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.

--master-language
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.

--no-previous
This option removes --previous from the options passed to msgmerge. This is necessary
to support versions of gettext earlier than 0.16.

--previous
This option adds --previous to the options passed to msgmerge. It requires gettext
0.16 or later, and is activated by default.

CONFIGURATION FILE

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.
The following example only produces 2 POT files: l10n/po/foo.pot (containing the material
from foo/gui.xml) and l10n/po/bar.pot (containing the material from both bar/gui.xml and
bar/cli.xml).

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

Example

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 \
add_fr:doc/l10n/script.fr.add

You can also use language templates as follow:

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

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 \
$lang:book.$lang.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.

AUTHORS

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

COPYRIGHT AND LICENSE

       Copyright 2002-2022 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).