w：Show who is logged on and what they are doing
查看当前登录用户以及用户在做什么
[root@www ~]# w 11:02:41 up 4 days, 2:05, 3 users, load average: 0.00, 0.00, 0.00 #系统启动时间，运行多久，几个用户登录，平均负载 USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT root pts/0 192.168.146.1 03:45 0.00s 0.38s 0.00s w root pts/1 192.168.146.1 09:09 2:00 0.04s 0.00s -bash zhangsan pts/2 192.168.146.1 11:01 1:40 0.00s 0.00s -bash
who：show who is logged on
查看谁正在登录系统
[root@www ~]# who root pts/0 2018-09-05 03:45 (192.168.146.1) root pts/1 2018-09-05 09:09 (192.168.146.1) zhangsan pts/2 2018-09-05 11:01 (192.168.146.1)
last：show listing of last logged in users
展示目前和上次登录系统的用户，读取的文件是/var/log/wtmp
[root@www ~]# last zhangsan pts/2 192.168.146.1 Wed Sep 5 11:01 still logged in root pts/1 192.168.146.1 Wed Sep 5 09:09 still logged in root pts/0 192.168.146.1 Wed Sep 5 03:45 still logged in root pts/1 192.168.146.1 Sun Sep 2 11:24 - 11:34 (00:09) root pts/0 192.168.146.1 Sun Sep 2 11:20 - 11:34 (00:14) 开始登录的时间 离开的时间 登录的总时间
lastlog：reports the most recent login of all users or of a given user
检查系统中所有用户上次登录的记录，读取的文件是/var/log/lastlog
[root@www ~]# lastlog 用户名 端口 来自 最后登陆时间 root pts/0 192.168.146.1 三 9月 5 11:13:30 +0800 2018 mysql **从未登录过** zhangsan pts/2 192.168.146.1 三 9月 5 11:01:01 +0800 2018 lisi **从未登录过**