1. 获取登录信息 - w / who / last/ lastb。

      2.  23:31:16 up 12:16,  2 users,  load average: 0.00, 0.01, 0.05
      3. USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT
      4. root     pts/0    182.139.66.250   23:03    4.00s  0.02s  0.00s w
      5. jackfrue pts/1    182.139.66.250   23:26    3:56   0.00s  0.00s -bash
      6. [root ~]# who
      7. root     pts/0        2018-04-12 23:03 (182.139.66.250)
      8. jackfrued pts/1        2018-04-12 23:26 (182.139.66.250)
      9. [root ~]# who am i
      10. root     pts/0        2018-04-12 23:03 (182.139.66.250)
      11. [root ~]# who mom likes
      12. root     pts/0        2018-04-12 23:03 (182.139.66.250)
      13. [root ~]# last
      14. root     pts/0        117.136.63.184   Sun May 26 18:57   still logged in   
      15. reboot   system boot  3.10.0-957.10.1. Mon May 27 02:52 - 19:10  (-7:-42)   
      16. root     pts/4        117.136.63.184   Sun May 26 18:51 - crash  (08:01)    
      17. root     pts/4        117.136.63.184   Sun May 26 18:49 - 18:49  (00:00)    
      18. root     pts/3        117.136.63.183   Sun May 26 18:35 - crash  (08:17)    
      19. root     pts/2        117.136.63.183   Sun May 26 18:34 - crash  (08:17)    
      20. root     pts/0        117.136.63.183   Sun May 26 18:10 - crash  (08:42)

    2. 查看自己使用的Shell - ps。

      Shell也被称为“壳”或“壳程序”，它是用户与操作系统内核交流的翻译官，简单的说就是人与计算机交互的界面和接口。目前很多Linux系统默认的Shell都是bash（Bourne Again SHell），因为它可以使用tab键进行命令和路径补全、可以保存历史命令、可以方便的配置环境变量以及执行批处理操作。

      1. [root ~]# ps
      2.   PID TTY          TIME CMD
      3.  3531 pts/0    00:00:00 bash
      4.  3553 pts/0    00:00:00 ps

    4. 查看帮助文档 - man / info / —help / apropos。

      1. [root@izwz97tbgo9lkabnat2lo8z ~]# ps --help
      2. Usage:
      4.  Try 'ps --help <simple|list|output|threads|misc|all>'
      5.   or 'ps --help <s|l|o|t|m|a>'
      6.  for additional help text.
      7. For more details see ps(1).
      8. [root@izwz97tbgo9lkabnat2lo8z ~]# man ps
      9. PS(1)                                User Commands                                PS(1)
      10. NAME
      11.        ps - report a snapshot of the current processes.
      12. SYNOPSIS
      13.        ps [options]
      14. DESCRIPTION
      15. ...

    5. 查看系统和主机名 - uname / hostname。

      1. [root@izwz97tbgo9lkabnat2lo8z ~]# uname
      2. Linux
      3. [root@izwz97tbgo9lkabnat2lo8z ~]# hostname
      4. izwz97tbgo9lkabnat2lo8z
      5. [root@iZwz97tbgo9lkabnat2lo8Z ~]# cat /etc/centos-release
      6. CentOS Linux release 7.6.1810 (Core)

    6. 时间和日期 - date / cal。

      1. Shutdown scheduled for Sun 2019-05-26 19:34:27 CST, use 'shutdown -c' to cancel.
      2. [root ~]# 
      3. Broadcast message from root (Sun 2019-05-26 19:29:27 CST):
      5. The system is going down for power-off at Sun 2019-05-26 19:34:27 CST!
      6. [root ~]# shutdown -c
      8. Broadcast message from root (Sun 2019-05-26 19:30:22 CST):
      10. The system shutdown has been cancelled at Sun 2019-05-26 19:31:22 CST!
      11. [root ~]# shutdown -r 23:58
      12. Shutdown scheduled for Sun 2019-05-26 23:58:00 CST, use 'shutdown -c' to cancel.
      13. [root ~]# shutdown -c
      15. Broadcast message from root (Sun 2019-05-26 19:31:06 CST):
      17. The system shutdown has been cancelled at Sun 2019-05-26 19:32:06 CST!

    8. 退出登录 - exit / logout。

    9. 查看历史命令 - history。

      1. [root@iZwz97tbgo9lkabnat2lo8Z ~]# history
      2. ...
      3. 452  ls
      4. 453  cd Python-3.6.5/
      5. 454  clear
      6. 455  history
      7. [root@iZwz97tbgo9lkabnat2lo8Z ~]# !454