Index[SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [R] [S] [T] [U] [V] [W] [X] [Z] UID ul umask 2nd umount 2nd umount () unalias 2nd 3rd unhash uniq unlink () 2nd unset until URL user ID 2nd 3rd 4th effective 2nd 3rd 4th 5th real 2nd root set user ID 2nd 3rd 4th 5th user mode useradd userdel users uucp |