Linux基础：su命令使用方法介绍

清疚 2022-11-29 13:24 479阅读 0赞

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这篇文章通过具体的示例来介绍Linux下su命令的常见用法。

# 事前准备 #

*  准备如下用户

<table> 
 <thead> 
  <tr> 
   <th>用户名</th> 
   <th>密码</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>liumiao</td> 
   <td>liumiaocn</td> 
  </tr> 
  <tr> 
   <td>liumiaocn</td> 
   <td>liumiaocn</td> 
  </tr> 
 </tbody> 
</table>

*  操作系统：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: 切换用户 #

su是switch user的缩写，自然就是完成切换用户之用，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]$

注意事项：

*  从root切换为其他用户，不需密码输入，否则需要输入密码
 *  su 用户名 和 su - 用户名方式的区别在于是否读入用户配置信息

[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: 非交互式输入密码 #

如果希望嵌在脚本中，则往往需要使用非交互方式输入密码，可考虑使用如下方式：

[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: 指定用户执行指定命令 #

或者

# 用法4: su -切换为root用户 #

[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: 使用当前环境变量切换用户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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