lupdate
Usage: lupdate myproject.pro
lupdate is a command line tool that finds the translatable strings in the specified source, header and Qt Designer interface files, and produces or updates .ts translation files. The files to process and the files to update can be set at the command line, or provided in a .pro file specified as an command line argument. The produced translation files are given to the translator who uses Qt Linguist to read the files and insert the translations.
Companies that have their own translators in-house may find it useful to run lupdate regularly, perhaps monthly, as the application develops. This will lead to a fairly low volume of translation work spread evenly over the life of the project and will allow the translators to support a number of projects simultaneously.
Companies that hire in translators as required may prefer to run lupdate only a few times in the application's life cycle, the first time might be just before the first test phase. This will provide the translator with a substantial single block of work and any bugs that the translator detects may easily be included with those found during the initial test phase. The second and any subsequent lupdate runs would probably take place during the final beta phase.
The TS file format is a simple human-readable XML format that can be used with version control systems if required. lupdate can also process Localization Interchange File Format (XLIFF) format files; files in this format typically have file names that end with the .xlf suffix.
Pass the -help option to lupdate to obtain the list of supported options:
Usage:
lupdate [options] [project-file]
lupdate [options] [source-file|path]... -ts ts-files
Options:
-help Display this information and exit.
-noobsolete
Drop all obsolete strings.
-extensions <ext>[,<ext>]...
Process files with the given extensions only.
The extension list must be separated with commas, not with whitespace.
Default: 'ui,c,c++,cc,cpp,cxx,ch,h,h++,hh,hpp,hxx'.
-pluralonly
Only include plural form messages.
-silent
Do not explain what is being done.
-version
Display the version of lupdate and exit.
Qt Linguist is also able to import and export XLIFF files. See the Translators section for more information.
lrelease
Usage: lrelease myproject.pro
lrelease is a command line tool that produces QM files out of TS files. The QM file format is a compact binary format that is used by the localized application. It provides extremely fast lookups for translations. The TS files lrelease processes can be specified at the command line, or given indirectly by a Qt .pro project file.
This tool is run whenever a release of the application is to be made, from initial test version through to final release version. If the QM files are not created, e.g. because an alpha release is required before any translation has been undertaken, the application will run perfectly well using the text the programmers placed in the source files. Once the QM files are available the application will detect them and use them automatically.
Note that lrelease will only incorporate translations that are marked as "finished". Otherwise the original text will be used instead.
Pass the -help option to lrelease to obtain the list of supported options:
Usage:
lrelease [options] project-file
lrelease [options] ts-files [-qm qm-file]
Options:
-help Display this information and exit
-compress
Compress the QM files
-nounfinished
Do not include unfinished translations
-removeidentical
If the translated text is the same as
the source text, do not include the message
-silent
Do not explain what is being done
-version
Display the version of lrelease and exit
Missing Translations
Both lupdate and lrelease may be used with TS translation source files which are incomplete. Missing translations will be replaced with the native language phrases at runtime.
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