Current Perforce username.

By default, the Perforce username is the same as the OS username.

If a particular Perforce user does not have a password set, then any other Perforce user can impersonate this user by using the -u option with their Perforce commands. To prevent this, users should set their password with the p4 user or p4 passwd command.

If a user has set their Perforce password, you can still run commands as that user (if you know the password) with p4 -u username -P password command.

Perforce superusers can impersonate users without knowing their passwords. For more information, see the Perforce Server Administrator's Guide: Fundamentals.