• Check a .po file:

    $ msgfmt -c -v -o /dev/null file.po
  • Wipe out a .po file and keep only translated messages:

    $ msgattrib --translated -o cleaned.po messy.po
  • Delete duplicate messages in a .po file:

    $ msguniq -o no_duplicate.po duplicate_content.po
  • Show differences between two .po files (thanks to Jérome!):

    $ msgcat -u file1.po file2.po > diff.po
  • Generate a .mo file from a .po file:

    $ msgfmt -o target.mo source.po
  • If you want to have command-line tools use raw string instead of localized ones, add the following directives to your ~/.bash_profile:

    $ export LANGUAGE=C
    $ export LANG=C
    $ export LC_MESSAGES=C