1. id

[root@centos cmdtest]# id
uid=0(root) gid=0(root) groups=0(root) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
[root@centos cmdtest]#

2. who

# 显示正从192.168.0.13用root用户登录
[lihg@centos cmdtest]$ who
root     pts/0        2022-03-10 07:59 (192.168.0.13)

2-1. 属性 -H

# 显示列的标题
[lihg@centos cmdtest]$ who -H
NAME     LINE         TIME             COMMENT
root     pts/0        2022-03-10 07:59 (192.168.0.13)

2-2. 属性 -r

# 打印linux的运行级别
[lihg@centos cmdtest]$ who -Hr
NAME     LINE         TIME             IDLE          PID COMMENT
         run-level 3  2022-03-09 21:33

2-3. 属性 -b

# 打印机器的启动时间
[lihg@centos cmdtest]$ who -Hb
NAME     LINE         TIME                    PID COMMENT
         system boot  2022-03-09 21:33

2-4. 属性 -d

# 打印dead processes
[lihg@centos cmdtest]$ who -Hd
NAME     LINE         TIME             IDLE          PID COMMENT  EXIT
         pts/1        2022-03-11 06:33              2150 id=ts/1  term=0 exit=0

2-5. 属性 -a

[lihg@centos cmdtest]$ who -Ha
NAME       LINE         TIME             IDLE          PID COMMENT  EXIT
           system boot  2022-03-09 21:33
LOGIN      tty1         2022-03-09 21:33               697 id=tty1
           run-level 3  2022-03-09 21:33
root     + pts/0        2022-03-10 07:59   .          1311 (192.168.0.13)
           pts/1        2022-03-11 06:33              2150 id=ts/1  term=0 exit=0

[lihg@centos cmdtest]$ who -Hbdlrtu
NAME     LINE         TIME             IDLE          PID COMMENT  EXIT
         system boot  2022-03-09 21:33
LOGIN    tty1         2022-03-09 21:33               697 id=tty1
         run-level 3  2022-03-09 21:33
root     pts/0        2022-03-10 07:59   .          1311 (192.168.0.13)
         pts/1        2022-03-11 06:33              2150 id=ts/1  term=0 exit=

3. logname

# logname和id 显示的都是root
[root@centos cmdtest]# logname
root
[root@centos cmdtest]# id
uid=0(root) gid=0(root) groups=0(root) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023

# switch user到lihg，logname显示的还是root，但是id显示的是lihg的信息
[root@centos cmdtest]# su lihg
[lihg@centos cmdtest]$ logname 
root
[lihg@centos cmdtest]$ id
uid=1000(lihg) gid=1000(lihg) groups=1000(lihg),995(nginx) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
[lihg@centos cmdtest]$

4. whoami

[root@centos cmdtest]# whoami
root

[root@centos cmdtest]# su lihg

[lihg@centos cmdtest]$ whoami
lihg

who am i

这个看起来跟whoami好像一样，其实内容有差别。

whoami：显示的是当前用户
who am i：显示的是登录用户

[root@centos cmdtest]# who
root     pts/0        2022-03-10 07:59 (192.168.0.13)
[root@centos cmdtest]# whoami
root
[root@centos cmdtest]# who am i
root     pts/0        2022-03-10 07:59 (192.168.0.13)
[root@centos cmdtest]# su lihg
[lihg@centos cmdtest]$ whoami
lihg
[lihg@centos cmdtest]$ who am i
root     pts/0        2022-03-10 07:59 (192.168.0.13)
[lihg@centos cmdtest]$

5. w

[root@centos cmdtest]# w
 12:00:34 up 1 day,  4:51,  2 users,  load average: 0.00, 0.02, 0.05
USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT
root     pts/0    192.168.0.13     Thu07    2.00s  0.25s  0.00s w
lihg     pts/1    192.168.0.13     12:00   10.00s  0.00s  0.00s -bash