概述
本文介绍who， w， whoami 和 who am i的区别
实际输出
当前是root用户：
root@node77:~# w
18:20:21 up 7:57, 3 users, load average: 1.06, 1.51, 1.82
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
root pts/0 1.6.72.76 10:28 4.00s 1.89s 0.02s w
root pts/1 10.10.10.76 15:27 2:30m 0.09s 0.09s -bash
root pts/2 172.17.74.95 18:13 6:21 0.09s 0.09s -bash
root@node77:~#
root@node77:~#
root@node77:~#
root@node77:~# who
root pts/0 2012-04-19 10:28 (1.6.72.76)
root pts/1 2012-04-19 15:27 (10.10.10.76)
root pts/2 2012-04-19 18:13 (172.17.74.95)
root@node77:~#
root@node77:~# who am i
root pts/0 2012-04-19 10:28 (1.6.72.76)
root@node77:~#
root@node77:~#
root@node77:~# whoami
root
切换到test01用户：
root@node77:~# su - test01
test01@node77:~$ who am i
root pts/0 2012-04-19 10:28 (1.6.72.76)
test01@node77:~$
test01@node77:~$ whoami
test01
test01@node77:~$
具体区别
w: Show who is logged on and what they are doing
who: Show who is logged on
whoami: Print effective userid(EUID)
who am i： Print effective userid(UID), even use sudo to switch users
