l10n_check is a small utility to validate one or multiple java property files (.properties).
It is (as the name suggests) intended to validate localization files.
Thus, when multiple files are validated, missing keys and such are reported.

l10n_check [-v] [-nowarn] [ ...]
the optional -v (verbose) switch causes l10n_check to print all key-value pairs.
the optional -nowarn switch causes l10n_check to only print errors.

0 : Everything is ok (as far as l10n_check is concerned)
1 : Bad command-line parameters (no files supplied)
2 : There are validation errors