:~$ id
uid=1000(marc) gid=1000(marc) groups=4(adm),20(dialout),24(cdrom),25(floppy),29(audio),30(dip),44(video),46(plugdev),110(netdev),111(lpadmin),113(powerdev),114(scanner),117(admin),1000(marc)
:~$ id hal
id: hal: No such user
:~$ id haldeamon
id: haldeamon: No such user
:~$ uname -a
Linux deathstar-laptop 2.6.22-12-generic #1 SMP Sun Sep 23 18:11:30 GMT 2007 i686 GNU/Linux
:~$ id 4(adm), 20(dialout) ,24(cdrom) ,25(floppy) ,29(audio) ,30(dip) ,44(video) ,46(plugdev) ,110(netdev) ,111(lpadmin) ,113(powerdev) ,114(scanner) ,117(admin) ,1000(marc)
uid=1000(marc) gid=1000(marc) groups=
:~$ id hal
id: hal: No such user
:~$ id haldeamon
id: haldeamon: No such user
:~$ uname -a
Linux deathstar-laptop 2.6.22-12-generic #1 SMP Sun Sep 23 18:11:30 GMT 2007 i686 GNU/Linux