Display information about yourself or another user: user ID, group ID, effective user ID and group ID if relevant, and additional group IDs.
Print group ID only.
Print supplementary groups only.
With -u, -g, or -G, print user or group name, not number.
With -u, -g, or -G, print real, not effective, user ID or group ID.
Print user ID only.
Print help message and then exit.
Print version information.