Command-Line Interface

Babel includes a command-line interface for working with message catalogs, similar to the various GNU gettext tools commonly available on Linux/Unix systems.

When properly installed, Babel provides a script called pybabel:

$ pybabel --help
usage: pybabel command [options] [args]

options:
  --version       show program's version number and exit
  -h, --help      show this help message and exit
  --list-locales  print all known locales and exit
  -v, --verbose   print as much as possible
  -q, --quiet     print as little as possible

commands:
  compile  compile message catalogs to MO files
  extract  extract messages from source files and generate a POT file
  init     create new message catalogs from a POT file
  update   update existing message catalogs from a POT file

The pybabel script provides a number of sub-commands that do the actual work. Those sub-commands are described below.

compile

The compile sub-command can be used to compile translation catalogs into binary MO files:

$ pybabel compile --help
usage: pybabel compile [options]

compile message catalogs to MO files

options:
  -h, --help            show this help message and exit
  -D DOMAIN, --domain=DOMAIN
                        domain of MO and PO files (default 'messages')
  -d DIR, --directory=DIR
                        base directory of catalog files
  -l LOCALE, --locale=LOCALE
                        locale of the catalog
  -i FILE, --input-file=FILE
                        name of the input file
  -o FILE, --output-file=FILE
                        name of the output file (default
                        '<output_dir>/<locale>/LC_MESSAGES/<domain>.mo')
  -f, --use-fuzzy       also include fuzzy translations (default False)
  --statistics          print statistics about translations

If directory is specified, but output-file is not, the default filename of the output file will be:

<directory>/<locale>/LC_MESSAGES/<domain>.mo

If neither the input_file nor the locale option is set, this command looks for all catalog files in the base directory that match the given domain, and compiles each of them to MO files in the same directory.

extract

The extract sub-command can be used to extract localizable messages from a collection of source files:

$ pybabel extract --help
usage: pybabel extract [options] dir1 <dir2> ...

extract messages from source files and generate a POT file

options:
  -h, --help            show this help message and exit
  --charset=CHARSET     charset to use in the output (default "utf-8")
  -k KEYWORDS, --keyword=KEYWORDS
                        keywords to look for in addition to the defaults. You
                        can specify multiple -k flags on the command line.
  --no-default-keywords
                        do not include the default keywords
  -F MAPPING_FILE, --mapping=MAPPING_FILE
                        path to the extraction mapping file
  --no-location         do not include location comments with filename and
                        line number
  --omit-header         do not include msgid "" entry in header
  -o OUTPUT, --output=OUTPUT
                        path to the output POT file
  -w WIDTH, --width=WIDTH
                        set output line width (default 76)
  --no-wrap             do not break long message lines, longer than the
                        output line width, into several lines
  --sort-output         generate sorted output (default False)
  --sort-by-file        sort output by file location (default False)
  --msgid-bugs-address=EMAIL@ADDRESS
                        set report address for msgid
  --copyright-holder=COPYRIGHT_HOLDER
                        set copyright holder in output
  -c TAG, --add-comments=TAG
                        place comment block with TAG (or those preceding
                        keyword lines) in output file. One TAG per argument
                        call

init

The init sub-command creates a new translations catalog based on a PO template file:

$ pybabel init --help
usage: pybabel init [options]

create new message catalogs from a POT file

options:
  -h, --help            show this help message and exit
  -D DOMAIN, --domain=DOMAIN
                        domain of PO file (default 'messages')
  -i FILE, --input-file=FILE
                        name of the input file
  -d DIR, --output-dir=DIR
                        path to output directory
  -o FILE, --output-file=FILE
                        name of the output file (default
                        '<output_dir>/<locale>/LC_MESSAGES/<domain>.po')
  -l LOCALE, --locale=LOCALE
                        locale for the new localized catalog

update

The update sub-command updates an existing new translations catalog based on a PO template file:

$ pybabel update --help
usage: pybabel update [options]

update existing message catalogs from a POT file

options:
  -h, --help            show this help message and exit
  -D DOMAIN, --domain=DOMAIN
                        domain of PO file (default 'messages')
  -i FILE, --input-file=FILE
                        name of the input file
  -d DIR, --output-dir=DIR
                        path to output directory
  -o FILE, --output-file=FILE
                        name of the output file (default
                        '<output_dir>/<locale>/LC_MESSAGES/<domain>.po')
  -l LOCALE, --locale=LOCALE
                        locale of the translations catalog
  --ignore-obsolete     do not include obsolete messages in the output
                        (default False)
  -N, --no-fuzzy-matching
                        do not use fuzzy matching (default False)
  --previous            keep previous msgids of translated messages (default
                        False)

If output_dir is specified, but output-file is not, the default filename of the output file will be:

<directory>/<locale>/LC_MESSAGES/<domain>.mo

If neither the output_file nor the locale option is set, this command looks for all catalog files in the base directory that match the given domain, and updates each of them.