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Translations in Ubuntu (from a developer perspective)

This page tries to outline

• how Ubuntu deals with translations (and i18n in general) from a developer's perspective
• which tools are interesting for developers to make sure that translations and i18n work fine

General information

Be sure to read TranslationLifecycle in the translations wiki pages for a general overview of how translations work in Ubuntu.

Language Packs

General

Packages in main and restricted don't contain translations (*.mo) files themselves, they are stripped during the build on the Launchpad buildds and put into language-pack-* packages instead. This is done in an attempt to bundle the translations you're interested in and cut down the occupied space.

Note: once a package is promoted to main, it only needs to be rebuilt the first time after promotion so that pkgbinarymangler can strip the translations. After this, import to Launchpad Translations and export in language packs "will just happen".

Comparing the contents of a package built by Launchpad Soyuz and a locally built one:

daniel@bert:~$ debdiff --nocontrol gcalctool_5.27.2-0ubuntu1_amd64.deb /var/cache/pbuilder/result/gcalctool_5.27.2-0ubuntu1_amd64.deb 
[The following lists of changes regard files as different if they have
different names, permissions or owners.]

Files in second .deb but not in first
-------------------------------------
-rw-r--r--  root/root   /usr/share/locale/af/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/am/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/ar/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/as/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/ast/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/az/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/be/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/be@latin/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/bg/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/bn/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/bn_IN/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/bs/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/ca/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/ca@valencia/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/cs/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/cy/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/da/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/de/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/dz/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/el/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/en_CA/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/en_GB/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/en_US/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/es/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/et/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/eu/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/fa/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/fi/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/fr/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/ga/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/gl/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/gu/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/he/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/hi/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/hr/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/hu/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/id/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/it/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/ja/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/ka/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/kn/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/ko/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/ku/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/lt/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/lv/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/mai/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/mg/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/mk/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/ml/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/mn/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/mr/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/ms/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/nb/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/ne/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/nl/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/nn/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/oc/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/or/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/pa/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/pl/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/pt/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/pt_BR/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/ro/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/ru/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/rw/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/si/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/sk/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/sl/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/sq/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/sr/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/sr@latin/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/sv/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/ta/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/te/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/th/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/tk/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/tr/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/uk/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/vi/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/xh/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/zh_CN/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/zh_HK/LC_MESSAGES/gcalctool.mo
-rw-r--r--  root/root   /usr/share/locale/zh_TW/LC_MESSAGES/gcalctool.mo
daniel@bert:~$ 

Translations Templates

For pkgstriptranslations (in the pkgbinarymangler package) to do the job right, please make sure that your package in main or restricted builds a .pot during the build. It does not necessarily need to be shipped in the source or in the binary package. Generating it during the build is good enough. This can be achieved by running the following in debian/rules:

• For GNOME packages:

cd po; intltool-update -p

If there's more than one ./po/ directory (or it has a different name), please make sure to adjust the call above.

• For KDE packages:

TODO

• For GNU packages:

TODO: check

make update-po

Verifying translation uploads

This information is intended to help package maintainers to optimize their packages, so that translation related files get automatically imported into Launchpad.

To test if your package conforms to the requirements of the import script in Launchpad, please do the following:

1. install the 'pkgbinarymangler' package
2. in /etc/pkgbinarymangler/striptranslations.conf set 'enable:' to "true"
3. optionally install any build dependencies: sudo apt-get build-dep $PKGNAME
4. build your package with 'debuild -uc -us -b'
5. You will find a '-translations.tar.gz' tarball along with the .deb package(s)
6. untar that tarball into a temporary directory
7. compare if the directory structure and the .pot and .po files conform to the requirements listed below

Glossary:

• translation domain (domain)
  • The application requires translations to be in /usr/share/locale/$LOCALE/LC_MESSAGES/ or /usr/share/locale-langpack/$LOCALE/LC_MESSAGES/ when they are shipped in our language-packs. The filename is $TRANSLATION_DOMAIN.po . For example: the application 'nautilus' may expect its translations to use the translation domain 'nautilus'. Therefor the filename would be 'nautilus.mo'. The corresonding translation template should have the same translation domain in its filename, e.g. 'nautilus.pot'. The expected translation domain name can only be found in the source code of the application. The translation domain must be unique across all applications and packages. I.e. something generic like 'messages.pot' won't work.

If the application uses gettext, like most GTK and GNU applications do:

• the filename of the .pot file should be the same as what the expected translation domain is.
• the actual translations (.po files) must have a filename of the format $LANGUAGECODE.po or $LOCALECODE.po (e.g. de.po, pt_BR.po, zh_TW.po)
• translation related files (.pot and the corresponding .po files) must end up in the same (sub-)directory.
• if the application has multiple translation domains (i.e. multiple .pot files), each .pot file and their corresponding .po files should end up in a separate subdirectory (e.g. po/nautilus/nautilus.pot and po/libnautilus/libnautilus.pot)
• templates and translations for the main application or library should go into po/.
• templates and translations for help files should go into help/po/. They will be ignored by Launchpad, since we currently have no infrastructure to deal with them properly.
• templates and translations for documentation files should go into doc/po/. They will also be ignored by Launchpad for the same reason as the help translations.
• if there are .po files present but no associated .pot template, remove them. They are useless without a .pot template. There might be a bug in the package or in the source code that the .pot file doesn't get generated.
• Please check if the .pot file has any meaningful content. Empty .pot files should be removed and the package build rules being fixed.
• if your package contains patches and those patches result into extra templates, like 'patches.pot', please merge those changes into the main template, as we have no use for patch .pot files. Such .pot files should not exist in the final tarball.
• If the package generates multiple .pot files and later merges them into one, only the final .pot file should be present in the final tarball. The other ones are useless.
• If the package creates the same .pot file in architecture dependent subdirectories, please consider to merge them, as we can only deal with one single .pot per translation domain.
• test routines and test files should not generate any .pot template or ship any .po file. If such files are present, please remove them.
• if you have multiple .po files for a language, each in a different encoding, please consider renaming the ones encoded in UTF-8 to be the main .po file for that laguage and throw away the others. They are maybe intersting for Wndows users, but not for Linux users, since translations get converted with iconv into the encoding the user is runnning anyways. And nowadays, UTF-8 is the default encoding on Linux. Example: if you have zh_TW.po (Big5 encoding), zh_TW.UTF-8.po and zh_TW.cp960.po, please remove zh.po and zh.cp960.po and rename zh_TW.UTF-8.po to zh.po.
• no.po is obsolete. If you find that .po file, please look into it and find out if it's "Norwegian, Bokmål" or "Nynorsk". Usually it's Bokmål. Please rename the file to the proper language code: nb.po for Bokmål, nn.po for Nynorsk. If nb.po and nn.po are already present, remove no.po.
• if you have a en_US.po file, please investigate, if it really contains translations (i.e. if the source code uses en_GB or another language) and if not, throw it away. It's useless in that case and only confuses translators and users alike.

Desktop Entries

Translations of desktop entries (.desktop files) are also stripped out and included in language packs.

Contrary to what other distros do (except currently OpenSUSE), the translations are not expected to be in the .desktop files themselves (static translations), but rather in the same .mo file of the application, from which they are then loaded at runtime. We do this in order to be able to translate them in Launchpad and to ship them in language packs, so that they can be edited and updated by Ubuntu translators.

The runtime loading is done by a patch in glib (or in kdelibs for Kubuntu), which recognises the the X-Ubuntu-Gettext-Domain additional key we add to all Ubuntu .desktop files and adds gettext support when loading them. Note that if the .desktop file already contains translations, these static translations will be preferred.

As an example for this key in action, here's how it is done in the Transmission source package in Jaunty (from the 20_add_X-Ubuntu-Gettext-Domain.diff patch):

Index: transmission-1.40-2ubuntu1/gtk/transmission.desktop.in
===================================================================
--- transmission-1.40-2ubuntu1.orig/gtk/transmission.desktop.in 2008-12-09 18:57:13.000000000 +0000
+++ transmission-1.40-2ubuntu1/gtk/transmission.desktop.in      2008-12-09 18:58:54.000000000 +0000
@@ -9,3 +9,4 @@
 Type=Application
 MimeType=application/x-bittorrent;
 Categories=Network;FileTransfer;P2P;GTK;
+X-Ubuntu-Gettext-Domain=transmission

Note, however, that if the package is using the `langpack.mk` CDBS class (or the gnome.mk class, which includes it) it will generally not be necessary to use a patch for this, as langpack.mk will take care of it.

In summary, for packages in main we strip the translations out of the .desktop files, and gnome-panel (TODO: is this the right package?, TODO: how is this done in KDE?) has a patch to load a translation from the .mo file. It basically uses that key to figure out where to get the translation from.

Additional information:

• Original specification

• Original specification for KDE

Documentation

GNOME docs

KDE docs

K/Ubuntu docs

• See also DocumentationTeam/Translation

Xubuntu docs

Note: the Xubuntu docs have now moved to universe

The import queue

All translation templates (.pot files) and translations (.po) end up in the Launchpad Translations import queue before being imported into Launchpad.

Some of the Ubuntu import queues:

• Hardy

• Intrepid

• Jaunty

• Karmic

Templates generally get approved automatically, but sometimes there is some manual work involved in approving them. The Ubuntu Translations Coordinators Team manages the import queue. We've got a mailing list where issues can be discussed and we welcome the help of any community members experienced with translations.

General Advice

If you want to make sure that your packages translations are set up correctly, try running:

• For GNOME packages:

cd po; intltool-update -m

and be sure to either fix the issues or report them upstream.

Note: this is only worth trying if the package uses intltool for i18n (i.e. look for intltool.m4 in the top-level source directory)

• For GNU packages:
• For KDE packages:

Sometimes empty .po files caused packages to build from source.

Kubuntu-specific notes

Additional notes on packages not using the Gettext format

Mozilla

OpenOffice.org

CategoryUbuntuDevelopment