這篇文章通過具體的示例來介紹Linux下su命令的常見用法。

事前準備

• 準備如下用戶

用戶名密碼

liumiao	liumiaocn
liumiaocn	liumiaocn

• 操作系統：CentOS 7

[root@liumiaocn ~]# useradd liumiao [root@liumiaocn ~]# useradd liumiaocn [root@liumiaocn ~]# passwd liumiao Changing password for user liumiao. New password: BAD PASSWORD: The password contains the user name in some form Retype new password: passwd: all authentication tokens updated successfully. [root@liumiaocn ~]# [root@liumiaocn ~]# passwd liumiaocn Changing password for user liumiaocn. New password: BAD PASSWORD: The password contains the user name in some form Retype new password: passwd: all authentication tokens updated successfully. [root@liumiaocn ~]# [root@liumiaocn ~]# cat /etc/redhat-release CentOS Linux release 7.6.1810 (Core) [root@liumiaocn ~]#

用法1: 切換用戶

su是switch user的縮寫，自然就是完成切換用戶之用，比如：

[root@liumiaocn ~]# id uid=0(root) gid=0(root) groups=0(root) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [root@liumiaocn ~]# su liumiao [liumiao@liumiaocn root]$ id uid=1000(liumiao) gid=1000(liumiao) groups=1000(liumiao) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [liumiao@liumiaocn root]$

注意事項：

• 從root切換為其他用戶，不需密碼輸入，否則需要輸入密碼
• su 用戶名 和 su - 用戶名方式的區別在于是否讀入用戶配置信息

[liumiao@liumiaocn root]$ id uid=1000(liumiao) gid=1000(liumiao) groups=1000(liumiao) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [liumiao@liumiaocn root]$ [liumiao@liumiaocn root]$ su liumiaocn Password: [liumiaocn@liumiaocn root]$ id uid=1001(liumiaocn) gid=1001(liumiaocn) groups=1001(liumiaocn) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [liumiaocn@liumiaocn root]$

用法2: 非交互式輸入密碼

如果希望嵌在腳本中，則往往需要使用非交互方式輸入密碼，可考慮使用如下方式：

[liumiaocn@liumiaocn root]$ id uid=1001(liumiaocn) gid=1001(liumiaocn) groups=1001(liumiaocn) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [liumiaocn@liumiaocn root]$ su liumiao <<! > liumiaocn > id > ! Password: uid=1000(liumiao) gid=1000(liumiao) groups=1000(liumiao) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [liumiaocn@liumiaocn root]$ [liumiaocn@liumiaocn root]$ id uid=1001(liumiaocn) gid=1001(liumiaocn) groups=1001(liumiaocn) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [liumiaocn@liumiaocn root]$ [liumiaocn@liumiaocn root]$ id uid=1001(liumiaocn) gid=1001(liumiaocn) groups=1001(liumiaocn) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [liumiaocn@liumiaocn root]$ su - liumiao <<! > liumiaocn > id > ! Password: Last login: Fri Aug 21 08:49:21 EDT 2020 uid=1000(liumiao) gid=1000(liumiao) groups=1000(liumiao) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [liumiaocn@liumiaocn root]$ id uid=1001(liumiaocn) gid=1001(liumiaocn) groups=1001(liumiaocn) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [liumiaocn@liumiaocn root]$

用法3: 指定用戶執行指定命令

[liumiaocn@liumiaocn root]$ id uid=1001(liumiaocn) gid=1001(liumiaocn) groups=1001(liumiaocn) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [liumiaocn@liumiaocn root]$ su -l liumiao -c id Password: uid=1000(liumiao) gid=1000(liumiao) groups=1000(liumiao) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [liumiaocn@liumiaocn root]$

或者

[liumiaocn@liumiaocn root]$ id uid=1001(liumiaocn) gid=1001(liumiaocn) groups=1001(liumiaocn) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [liumiaocn@liumiaocn root]$ su -c id liumiao Password: uid=1000(liumiao) gid=1000(liumiao) groups=1000(liumiao) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [liumiaocn@liumiaocn root]$

用法4: su -切換為root用戶

[liumiaocn@liumiaocn root]$ su - Password: Last login: Fri Aug 21 08:38:34 EDT 2020 from gateway on pts/0 Last failed login: Fri Aug 21 08:47:59 EDT 2020 on pts/0 There was 1 failed login attempt since the last successful login. [root@liumiaocn ~]#

用法5: 使用當前環境變量切換用戶su -p

[liumiaocn@liumiaocn root]$ id uid=1001(liumiaocn) gid=1001(liumiaocn) groups=1001(liumiaocn) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 [liumiaocn@liumiaocn root]$ echo $HOME /home/liumiaocn [liumiaocn@liumiaocn root]$ su -p liumiao Password: bash: /home/liumiaocn/.bashrc: Permission denied bash-4.2$ echo $HOME /home/liumiaocn bash-4.2$ id uid=1000(liumiao) gid=1000(liumiao) groups=1000(liumiao) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 bash-4.2$

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