linux换源

yum换源：

1. 备份：

cd /etc/yum.repos.d

sudo mv CentOS-base.repo CentOS-base.repo.backup

  2.删除旧源

sudo rm -f /etc/yum.repos.d/CentOS-base.repo

  3.换源

# 阿里云

sudo wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

# 清华大学

sudo wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.tuna.tsinghua.edu.cn/repo/Centos-7.repo

# 中科大

sudo wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.ustc.edu.cn/repo/Centos-7.repo

4.epel扩展源
sudo wget -O /etc/yum.repos.d/epel.repo https://mirrors.aliyun.com/repo/epel-7.repo

5.清理缓存

sudo yum clean all

sudo yum makecache fast

6.验证

sudo yum repolist