System administration command. Create or update system users from entries in file. Each line in file has the same format as an entry in /etc/passwd except that passwords are unencrypted, and group IDs can be given as a name or number. During an update, the password age field is ignored if the user already exists in the /etc/shadow password file. If a group name or ID does not already exist, it will be created. If a home directory does not exist, it will be created.