1. A UNIX command that identifies the user account under which it is executed, including UID, GID, groups, and associated names. Key point: This is often the first command a hacker will run on the system when the hacker breaks in remotely. The hacker will remotely compromise a service that is running under either root account, a special account setup for that service (e.g. the majordomo service runs under a user account called "majordomo"), or a user's account. The hacker is hoping they have achieved root access immediately. If not, the hacker will have to run a local exploit in order to elevate privileges. The other popular command hackers might execute is id. Example: Running id as root on one of my systems results in: uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel),11(floppy) From Hacking-Lexicon

2. print real and effective UIDs and GIDs From whatis