查看登录的用户：
[root@yiyi-19-86 ~]# w
11:38:48 up 19 days, 16:21, 2 users, load average: 0.00, 0.03, 0.05
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
root pts/0 113.92.229.253 11:36 2:13 0.04s 0.04s -bash
root pts/2 113.92.229.253 11:38 0.00s 0.14s 0.09s w
修改密码： passwd
踢出登录的某个用户 ：
pkill -kill -t pts/0