20. User information

This section describes commands that print user-related information: logins, groups, and so forth.

20.1 id: Print real and effective uid and gid		Print real and effective uid and gid.
20.2 logname: Print current login name		Print current login name.
20.3 whoami: Print effective user id		Print effective user id.
20.4 groups: Print group names a user is in		Print group names a user is in.
20.5 users: Print login names of users currently logged in		Print login names of users currently logged in.
20.6 who: Print who is currently logged in		Print who is currently logged in.