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