id(1)

     NAME
          id - print real and effective UIDs and GIDs

     SYNOPSIS
          id [-gnruG] [--group] [--name] [--real] [--user] [--groups]
          [--help] [--version] [username]

     DESCRIPTION
          This documentation is no longer being maintained and may be
          inaccurate or incomplete.  The Texinfo documentation is now
          the authoritative source.

          This manual page documents the GNU version of id.  id prints
          information about the given user, or the process running it
          if no user is specified.  By default, it prints the real
          user ID, real group ID, effective user ID if different from
          the real user ID, effective group ID if different from the
          real group ID, and supplemental group IDs.  It prints each
          of these values preceded by a string identifying it and
          followed by the corresponding user or group name in
          parentheses.

          The options cause id to print only part of the above
          information.

        OPTIONS
          -g, --group
               Print only the group ID.

          -G, --groups
               Print only the supplementary groups.

          --help
               Print a usage message on standard output and exit
               successfully.

          -n, --name
               Print the user or group name instead of the ID number.
               Requires -u, -g, or -G.

          -r, --real
               Print the real, instead of effective, user or group ID.
               Requires -u, -g, or -G.

          -u, --user
               Print only the user ID.

          --version
               Print version information on standard output then exit
               successfully.