how to configure local Yum source and external network source in Linux

Local source configuration method

Go into /etc/yum.reps.d/ directory and create a file ending with .repo.The content like follow.

[base]
name=cdrom          #cdrom is notes.it can write casually.
baseurl=file:///mnt/    #local cdrom's path. path of the yum source.
enabled=1
gpgcheck=0        #Check the legitimacy of the yum source.when the value is 1,need follow line.
#gpgkey=URL #check url

use command yum clean all and yum repolist to make metadata.after these you can use local yum.

External network configuration method

1 backup the yum source that the system had when you install.
mv /etc/yum.repos.d/*.repo /etc/yum/repos.d/repo_backup/

2 download new yum source.
wget http://mirrors.aliyun.com/repo/Centos-7.repo
also use command yum clean all and yum repolist to make metadata

Or you can modify the source list file under Debian linux system.
vi /etc/apt/sources.list
add yum source address into it.For example:

#source address of Aliyun
deb http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse
 deb http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse
 deb http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse
 deb http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse
 deb http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse
 deb-src http://mirrors.aliyun.com/ubuntu/ trusty main restricted universe multiverse
 deb-src http://mirrors.aliyun.com/ubuntu/ trusty-security main restricted universe multiverse
 deb-src http://mirrors.aliyun.com/ubuntu/ trusty-updates main restricted universe multiverse
 deb-src http://mirrors.aliyun.com/ubuntu/ trusty-proposed main restricted universe multiverse
 deb-src http://mirrors.aliyun.com/ubuntu/ trusty-backports main restricted universe multiverse

run apt-get update.Then you can install software by new source.