The script has two modes of operation:
- rebuildMessages.php --update
- Updates any messages which were last edited by "MediaWiki default" to their current version. Creates any messages which did not exist.
- rebuildMessages.php --rebuild
- Updates all messages to their current default value, regardless of whether they have been manually edited. This is sometimes used on other wikis when a new messages file has just been created, with a comprehensive set of default messages. It has never been used on the English Wikipedia.
Older edits made by this script had a user ID of zero, so they are treated as anonymous edits in the page history, with a link to the user contributions instead of the user page. Newer edits have a nonzero user ID.
The same username is also used by the MediaWiki installer. Installing MediaWiki has the same effect as rebuildMessages.php --update.
If there is a problem with the text of the default messages, please file a bug report at http://bugzilla.wikimedia.org/.