id - print user/group ID
$ id [options...]
id outputs user and group information for the current user.
-u: Print only real UID.-g: Print only real GID.-G: Print only all GIDs.-n: If -u, -g or -G is specified, print full names instead of IDs.$ id
uid=100(anon) gid=100(users) groups=1(wheel),10(lookup),12(notify),4(audio),13(window),14(clipboard),3(phys)
$ id -u
100
$ id -g
100
$ id -un
anon
$ id -G
1 10 12 4 13 14 3