Linux steps to configure local yum source, configure domestic yum source, and configure epel source

mount -o loop /mnt/yum-iso/CentOS-7-x86_64-DVD-1611.iso /mnt/cdrom

#iso.repo must end with .repo[root@node5 ~]# cat /etc/yum.repos.d/iso.repo 
[iso]
name=iso
baseurl=file:///mnt/cdrom
enable=1
gpgcheck=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

#Clear all yum caches in the system [root@node5 yum.repos.d]# yum clean all

#Generate yum cache [root@node5 yum.repos.d]# yum makecache


#Notes:
[iso] #The name of the yum source, which is unique on this server and is used to distinguish different yum sources			
name= iso #Description of yum source baseurl=file:///mnt/cdrom #The path of yum source can also be FTP (ftp://...), HTTP (http://...), local (file:///the location of the CD-ROM mount directory)
enabled=1 #1 means enabling the yum source; 0 means disabling gpgcheck=0 #1 means using the public key to verify the correctness of the rpm package; 0 means not verifying gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7 #Specify the public key file address for rpm verification

#In the /etc/fstab file, add [root@node5 ~] to the last line# cat /etc/fstab
/dev/VolGroup00/LogVol00 / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/VolGroup00/LogVol01 swap swap defaults 0 0
/mnt/yum-iso/CentOS-7-x86_64-DVD-1611.iso /mnt/cdrom iso9660 loop 0 0

[root@node5 ~]# cd /etc/yum.repos.d/
[root@node5 yum.repos.d]# mkdir repo_bak
[root@node5 yum.repos.d]# mv *.repo repo_bak/
[root@node5 yum.repos.d]# ls
repo_bak

[root@node5 yum.repos.d]# wget http://mirrors.aliyun.com/repo/Centos-7.repo
[root@node5 yum.repos.d]# wget http://mirrors.163.com/.help/CentOS7-Base-163.repo
[root@node5 yum.repos.d]# ls
CentOS7-Base-163.repo Centos-7.repo repo_bak

#Note: There is a sentence in the Centos-7.repo file: baseurl=http://mirrors.aliyun.com/centos/$releasever/os/$basearch/
#$releasever indicates the system version number. You can use cat /etc/centos-release to view the version number. #[root@node5 yum.repos.d]# cat /etc/centos-release
#CentOS Linux release 7.4.1708 (Core)
#$basearch indicates the processor type, such as x86_64

#Clear all yum caches in the system [root@node5 yum.repos.d]# yum clean all

#Generate yum cache [root@node5 yum.repos.d]# yum makecache

#Install the official epel source [root@node5 yum.repos.d]# yum install -y epel-release

[root@node5 yum.repos.d]# ls
CentOS7-Base-163.repo Centos-7.repo epel.repo epel-testing.repo repo_bak

#Install Alibaba's epel source [root@node5 yum.repos.d]# wget -O /etc/yum.repos.d/epel-7.repo http://mirrors.aliyun.com/repo/epel-7.repo

[root@node5 yum.repos.d]# yum clean all

[root@node5 yum.repos.d]# yum makecache

[root@node5 yum.repos.d]# yum repolist enabled

[root@node5 yum.repos.d]# yum repolist all