忙着安装composer ，执行后，查看版本，报了这样一个提示：
[root@izuf60gbaaaq66y42r6y2fz ~]# composer --version
Do not run Composer as root/super user! See https://getcomposer.org/root for details
Composer version 1.6.5 2018-05-04 11:44:59
[root@izuf60gbaaaq66y42r6y2fz ~]# whoami
root
[root@izuf60gbaaaq66y42r6y2fz ~]#
大惊，怎么在root用户下执行了这一系列操作，确实很不像话，很不专业。于是，添加个普通用户：
adduser Abble
passwd
但，个人用户的权限有时远远满足不了开发需求。它只在home目录下有完整的权限，在其它目录下取决于root的授权。由于是个人开发，我希望Abble可以得到root的权限。于是，想起了sudo -s
[root@izuf60gbaaaq66y42r6y2fz ~]# su Abble
[Abble@izuf60gbaaaq66y42r6y2fz root]$ whoami
Abble
[Abble@izuf60gbaaaq66y42r6y2fz root]$ sudo -s
We trust you have received the usual lecture from the local System
Administrator. It usually boils down to these three things:
#1) Respect the privacy of others.
#2) Think before you type.
#3) With great power comes great responsibility.
[sudo] password for Abble:
Abble 不在 sudoers 文件中。此事将被报告。
很明显，执行失败。我们要在sudoers中配置一下：
[root@izuf60gbaaaq66y42r6y2fz ~]# whereis sudoers
sudoers: /etc/sudoers /etc/sudoers.d /usr/libexec/sudoers.so /usr/share/man/man5/sudoers.5.gz
[root@izuf60gbaaaq66y42r6y2fz ~]# vim /etc/sudoers
[root@izuf60gbaaaq66y42r6y2fz ~]#
## Allow root to run any commands anywhere
root ALL=(ALL) ALL
# Abble ALL=(ALL) ALL # 个人新增的一个用户，并且给它权限做事
Abble ALL=(ALL) NOPASSWD:ALL # 个人新增的一个用户，并且给它权限做事
如此，两个用户可以快速转化：
[Abble@izuf60gbaaaq66y42r6y2fz root]$ whoami
Abble
[Abble@izuf60gbaaaq66y42r6y2fz root]$ sudo -s
[root@izuf60gbaaaq66y42r6y2fz ~]# whoami
root
[root@izuf60gbaaaq66y42r6y2fz ~]# su Abble
[Abble@izuf60gbaaaq66y42r6y2fz root]$ whoami
Abble
[Abble@izuf60gbaaaq66y42r6y2fz root]$
