【背景】
折腾：
【未解决】Dovecot启动出错：dovecot Fatal Couldn’t parse private ssl_key Expecting ANY PRIVATE KEY
期间，需要去在CentOS 7中切换用户，到root，去执行对应的命令：
/usr/share/doc/dovecot-2.2.10/mkcert.sh
【折腾过程】
1.搜：
linux 切换用户
centos 7 切换用户
centos 7 switch user
参考：
ubuntu linux切换用户到root – 学习记录 – 博客频道 – CSDN.NET
Linux系统中切换用户身份su与sudo的用法与实例 – 斑马Linux – 51CTO技术博客
su – xxx
==su -l xxx
不指定用户，默认为root，所以：
su -
== su -l
== su -l root
去试试：
crifan@crifan:~$ ll /usr/share/doc/dovecot-2.2.10/ -rw-r--r-- 1 root root 931 Jun 26 2014 mkcert.sh crifan@crifan:~$ sudo /usr/share/doc/dovecot-2.2.10/mkcert.sh sudo: /usr/share/doc/dovecot-2.2.10/mkcert.sh: command not found crifan@crifan:~$ /usr/share/doc/dovecot-2.2.10/mkcert.sh -bash: /usr/share/doc/dovecot-2.2.10/mkcert.sh: Permission denied crifan@crifan:~$ su - Password: Last login: Sat Aug 15 14:53:40 CST 2015 on pts/1 Last failed login: Sat Aug 15 14:56:40 CST 2015 from 222.186.21.234 on ssh:notty There were 22 failed login attempts since the last successful login. [root@crifan ~]# chmod u+x //usr/share/doc/dovecot-2.2.10/mkcert.sh [root@crifan ~]# ll //usr/share/doc/dovecot-2.2.10/mkcert.sh -rwxr--r-- 1 root root 931 Jun 26 2014 //usr/share/doc/dovecot-2.2.10/mkcert.sh [root@crifan ~]# ll /usr/share/doc/dovecot-2.2.10/mkcert.sh -rwxr--r-- 1 root root 931 Jun 26 2014 /usr/share/doc/dovecot-2.2.10/mkcert.sh [root@crifan ~]# /usr/share/doc/dovecot-2.2.10/mkcert.sh Generating a 1024 bit RSA private key .........................++++++ ........++++++ writing new private key to '/etc/pki/dovecot/private/dovecot.pem' ----- subject= /OU=IMAP server/CN=imap.example.com/[email protected] SHA1 Fingerprint=A9:6C:7D:87:90:2F:5A:3C:F3:7A:EB:3D:A8:D4:EE:C6:FD:88:39:39 [root@crifan ~]# su -l crifan Last login: Sat Aug 15 14:56:32 CST 2015 on pts/1 crifan@crifan:~$
2.另外再去试试：
crifan@crifan:~$ su Password: [root@crifan crifan]# pwd /home/crifan [root@crifan crifan]# su -l crifan Last login: Sat Aug 15 14:58:05 CST 2015 on pts/1 crifan@crifan:~$ su -l Password: Last login: Sat Aug 15 15:01:21 CST 2015 on pts/1 [root@crifan ~]# su -l crifan Last login: Sat Aug 15 15:01:32 CST 2015 on pts/1 crifan@crifan:~$ su -l root Password: Last login: Sat Aug 15 15:01:42 CST 2015 on pts/1 Last failed login: Sat Aug 15 15:02:01 CST 2015 from 222.186.21.234 on ssh:notty There were 2 failed login attempts since the last successful login. [root@crifan ~]# su -l crifan Last login: Sat Aug 15 15:01:53 CST 2015 on pts/1 crifan@crifan:~$ su - Password: Last login: Sat Aug 15 15:02:02 CST 2015 on pts/1 Last failed login: Sat Aug 15 15:02:03 CST 2015 from 222.186.21.234 on ssh:notty There was 1 failed login attempt since the last successful login. [root@crifan ~]# su -l crifan Last login: Sat Aug 15 15:02:12 CST 2015 on pts/1
如图：
【总结】
从普通用户切换到root，算有三种：
- su
- 用su登录root后，不知道为何提示符变成了：
- [root@crifan crifan]#
- 多了个 crifan，觉得很奇怪，不懂。
- su –
- su -和su -l root好像是一样的。
- su -l root
- 推荐用此种，最完整的写法：su -l root
从root切换到普通用户：
su -l normal_username
比如：
[root@crifan ~]# su -l crifan Last login: Sat Aug 15 15:01:32 CST 2015 on pts/1
转载请注明：在路上 » 【已解决】Linux的CentOS 7系统中如何切换用户