[Content] guidelines
into the directory: cd
view the contents of the directory: ls
rename the backup: mv
downloaded from a network: wget
yum update: yum update
Before the first run yum install software, recommended updates yum.
1. Go to the source directory yum
command:
cd /etc/yum.repos.d
View the current yum source files in the directory:
command:
ll
2. "CentOS-Base.repo" Renaming backup "CentOS-Base.repo.old"
command:
mv CentOS-Base.repo CentOS-Base.repo.old
After the implementation can again list the files under the folder with ls, see "CentOS-Base.repo" has been renamed:

3. Download yum source from Ali cloud
command:
wget http://mirrors.aliyun.com/repo/Centos-7.repo

4. The new source renamed "CentOS-Base.repo"
command:
mv Centos-7.repo CentOS-Base.repo

5. Let yum re-cache the new data
command:
yum update -y

After a period of waiting, see the "finished!", The cursor stays in command input, on behalf of the update is successful:
