msgmerge

Msgmerge is a utility in the GNU gettext localization framework. It updates an existing translation file (.po) using updates from a reference file, typically a POT template or another PO file. By aligning on the msgid and, if present, the msgctxt, msgmerge integrates new messages while attempting to preserve existing translations.

During a merge, messages present in the reference that are not in the translation are added with empty translations. Messages that have changed in the reference may be reintroduced as fuzzy or flagged for translator review. The tool tries to preserve translator comments and extracted metadata; depending on options, it may remove obsolete entries or adjust fuzziness.

Common workflow: you maintain a POT template that reflects current source strings. When you modify source texts, run msgmerge to update your locale PO files, then translators fill in new strings. Example: msgmerge de.po app.pot -o de.po or to update in place: msgmerge -U de.po app.pot. For multiple languages you can repeat for each PO.

Msgmerge is one of several gettext tools used for localization workflow (along with msginit, msgfmt, xgettext). It requires gettext-tools to be installed.