新增一个普通用户并进入该用户：
[root@VM_0_7_centos ~]# groupadd mall [root@VM_0_7_centos ~]# useradd mall -m -d /home/mall -g mall -s /bin/bash [root@VM_0_7_centos ~]# passwd mall Changing password for user mall. New password: BAD PASSWORD: The password is shorter than 8 characters Retype new password: passwd: all authentication tokens updated successfully. [root@VM_0_7_centos ~]# su - mall
安装yum-utils失败了，提示需要root权限：
[mall@VM_0_7_centos ~]$ yum install -y yum-utils device-mapper-persistent-data lvm2 Loaded plugins: fastestmirror, langpacks You need to be root to perform this command.
使用sudo获取root权限：
[mall@VM_0_7_centos ~]$ sudo yum install -y yum-utils device-mapper-persistent-data lvm2 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 mall: mall is not in the sudoers file. This incident will be reported.
它说该普通用户没有在sudoers文件里，切换回root：
[mall@VM_0_7_centos ~]$ su - root Password: Last login: Wed Oct 30 16:00:38 CST 2019 from 202.101.145.54 on pts/1 Last failed login: Wed Oct 30 16:28:06 CST 2019 from 110.119.120.10 on ssh:notty There were 799 failed login attempts since the last successful login.
修改sudoers文件，加入写权限：
[root@VM_0_7_centos ~]# chmod +w /etc/sudoers [root@VM_0_7_centos ~]# vi /etc/sudoers
新增下面标红的那一行，把普通用户mall加进入：
敲:wq保存后，撤销sudoers文件写权限：
[root@VM_0_7_centos ~]# chmod -w /etc/sudoers
重新进入mall用户，下载yum-utils：
[root@VM_0_7_centos ~]# su - mall Last login: Wed Oct 30 16:23:23 CST 2019 on pts/0 [mall@VM_0_7_centos ~]$ sudo yum -y install yum-utils device-mapper-persistent-data 1vm2 [sudo] password for mall: Loaded plugins: fastestmirror, langpacks Loading mirror speeds from cached hostfile Package yum-utils-1.1.31-52.el7.noarch already installed and latest version Package device-mapper-persistent-data-0.8.5-1.el7.x86_64 already installed and latest version No package 1vm2 available. Nothing to do
这回可以了，不过其实已经安装过了，白折腾了。