Centos6 有俩个源，YUM源和EPEL扩展源，默认是没有配置EPEL扩展源的，需要手动添加，这个相当于第三方软件商店，可以安装一些第三方软件，YUM源的默认地址服务器是在海外，国内连接速度是比较慢的，有时候直接就是无法连接，导致工作不能继续下去，此时修改为国内的镜像站源后，就可以避免此情况的发生。
下面教程将会把YUM源和EPEL源都替换为腾讯云的，因为腾讯云的比阿里云的速度更快。
1、首先登录进去centos6的SSH终端里。
2、备份YUM源的原文件：
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup mv /etc/yum.repos.d/CentOS-Debuginfo.repo /etc/yum.repos.d/CentOS-Debuginfo.repo.backup mv /etc/yum.repos.d/CentOS-fasttrack.repo /etc/yum.repos.d/CentOS-fasttrack.repo.backup mv /etc/yum.repos.d/CentOS-Media.repo /etc/yum.repos.d/CentOS-Media.repo.backup mv /etc/yum.repos.d/CentOS-Vault.repo /etc/yum.repos.d/CentOS-Vault.repo.backup
3.创建EPEL源存放的文件：
touch epel.repo touch epel-testing.repo
4.替换腾讯云的源：
cat > /etc/yum.repos.d/CentOS-Base.repo <<'EOF'
# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client. You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
#
#
[base]
name=CentOS-$releasever - Base
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os&infra=$infra
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
#released updates
[updates]
name=CentOS-$releasever - Updates
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates&infra=$infra
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras&infra=$infra
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus&infra=$infra
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
#contrib - packages by Centos Users
[contrib]
name=CentOS-$releasever - Contrib
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib&infra=$infra
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
EOF
cat > /etc/yum.repos.d/CentOS-Debuginfo.repo <<'EOF'
# CentOS-Debug.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client. You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# All debug packages from all the various CentOS-5 releases
# are merged into a single repo, split by BaseArch
#
# Note: packages in the debuginfo repo are currently not signed
#
[base-debuginfo]
name=CentOS-6 - Debuginfo
baseurl=http://debuginfo.centos.org/6/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-Debug-6
enabled=0
EOF
cat > /etc/yum.repos.d/CentOS-fasttrack.repo <<'EOF'
[fasttrack]
name=CentOS-6 - fasttrack
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=fasttrack&infra=$infra
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/fasttrack/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
EOF
cat > /etc/yum.repos.d/CentOS-Media.repo <<'EOF'
# CentOS-Media.repo
#
# This repo can be used with mounted DVD media, verify the mount point for
# CentOS-6. You can use this repo and yum to install items directly off the
# DVD ISO that we release.
#
# To use this repo, put in your DVD and use it with the other repos too:
# yum --enablerepo=c6-media [command]
#
# or for ONLY the media repo, do this:
#
# yum --disablerepo=\* --enablerepo=c6-media [command]
[c6-media]
name=CentOS-$releasever - Media
baseurl=file:///media/CentOS/
file:///media/cdrom/
file:///media/cdrecorder/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
EOF
cat > /etc/yum.repos.d/CentOS-Vault.repo <<'EOF'
# CentOS-Vault.repo
#
# CentOS Vault holds packages from previous releases within the same CentOS Version
# these are packages obsoleted by the current release and should usually not
# be used in production
#-----------------
[C6.0-base]
name=CentOS-6.0 - Base
baseurl=http://vault.centos.org/6.0/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.0-updates]
name=CentOS-6.0 - Updates
baseurl=http://vault.centos.org/6.0/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.0-extras]
name=CentOS-6.0 - Extras
baseurl=http://vault.centos.org/6.0/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.0-contrib]
name=CentOS-6.0 - Contrib
baseurl=http://vault.centos.org/6.0/contrib/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.0-centosplus]
name=CentOS-6.0 - CentOSPlus
baseurl=http://vault.centos.org/6.0/centosplus/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
#-----------------
[C6.1-base]
name=CentOS-6.1 - Base
baseurl=http://vault.centos.org/6.1/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.1-updates]
name=CentOS-6.1 - Updates
baseurl=http://vault.centos.org/6.1/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.1-extras]
name=CentOS-6.1 - Extras
baseurl=http://vault.centos.org/6.1/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.1-contrib]
name=CentOS-6.1 - Contrib
baseurl=http://vault.centos.org/6.1/contrib/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.1-centosplus]
name=CentOS-6.1 - CentOSPlus
baseurl=http://vault.centos.org/6.1/centosplus/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
#-----------------
[C6.2-base]
name=CentOS-6.2 - Base
baseurl=http://vault.centos.org/6.2/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.2-updates]
name=CentOS-6.2 - Updates
baseurl=http://vault.centos.org/6.2/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.2-extras]
name=CentOS-6.2 - Extras
baseurl=http://vault.centos.org/6.2/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.2-contrib]
name=CentOS-6.2 - Contrib
baseurl=http://vault.centos.org/6.2/contrib/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.2-centosplus]
name=CentOS-6.2 - CentOSPlus
baseurl=http://vault.centos.org/6.2/centosplus/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
#-----------------
[C6.3-base]
name=CentOS-6.3 - Base
baseurl=http://vault.centos.org/6.3/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.3-updates]
name=CentOS-6.3 - Updates
baseurl=http://vault.centos.org/6.3/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.3-extras]
name=CentOS-6.3 - Extras
baseurl=http://vault.centos.org/6.3/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.3-contrib]
name=CentOS-6.3 - Contrib
baseurl=http://vault.centos.org/6.3/contrib/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.3-centosplus]
name=CentOS-6.3 - CentOSPlus
baseurl=http://vault.centos.org/6.3/centosplus/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
#-----------------
[C6.4-base]
name=CentOS-6.4 - Base
baseurl=http://vault.centos.org/6.4/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.4-updates]
name=CentOS-6.4 - Updates
baseurl=http://vault.centos.org/6.4/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.4-extras]
name=CentOS-6.4 - Extras
baseurl=http://vault.centos.org/6.4/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.4-contrib]
name=CentOS-6.4 - Contrib
baseurl=http://vault.centos.org/6.4/contrib/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.4-centosplus]
name=CentOS-6.4 - CentOSPlus
baseurl=http://vault.centos.org/6.4/centosplus/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
#-----------------
[C6.5-base]
name=CentOS-6.5 - Base
baseurl=http://vault.centos.org/6.5/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.5-updates]
name=CentOS-6.5 - Updates
baseurl=http://vault.centos.org/6.5/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.5-extras]
name=CentOS-6.5 - Extras
baseurl=http://vault.centos.org/6.5/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.5-contrib]
name=CentOS-6.5 - Contrib
baseurl=http://vault.centos.org/6.5/contrib/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.5-centosplus]
name=CentOS-6.5 - CentOSPlus
baseurl=http://vault.centos.org/6.5/centosplus/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
#-----------------
[C6.6-base]
name=CentOS-6.6 - Base
baseurl=http://vault.centos.org/6.6/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.6-updates]
name=CentOS-6.6 - Updates
baseurl=http://vault.centos.org/6.6/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.6-extras]
name=CentOS-6.6 - Extras
baseurl=http://vault.centos.org/6.6/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.6-contrib]
name=CentOS-6.6 - Contrib
baseurl=http://vault.centos.org/6.6/contrib/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.6-centosplus]
name=CentOS-6.6 - CentOSPlus
baseurl=http://vault.centos.org/6.6/centosplus/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
#-----------------
[C6.7-base]
name=CentOS-6.7 - Base
baseurl=http://vault.centos.org/6.7/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.7-updates]
name=CentOS-6.7 - Updates
baseurl=http://vault.centos.org/6.7/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.7-extras]
name=CentOS-6.7 - Extras
baseurl=http://vault.centos.org/6.7/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.7-contrib]
name=CentOS-6.7 - Contrib
baseurl=http://vault.centos.org/6.7/contrib/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.7-centosplus]
name=CentOS-6.7 - CentOSPlus
baseurl=http://vault.centos.org/6.7/centosplus/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
#-----------------
[C6.8-base]
name=CentOS-6.8 - Base
baseurl=http://vault.centos.org/6.8/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.8-updates]
name=CentOS-6.8 - Updates
baseurl=http://vault.centos.org/6.8/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.8-extras]
name=CentOS-6.8 - Extras
baseurl=http://vault.centos.org/6.8/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.8-contrib]
name=CentOS-6.8 - Contrib
baseurl=http://vault.centos.org/6.8/contrib/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.8-centosplus]
name=CentOS-6.8 - CentOSPlus
baseurl=http://vault.centos.org/6.8/centosplus/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
#-----------------
[C6.9-base]
name=CentOS-6.9 - Base
baseurl=http://vault.centos.org/6.9/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.9-updates]
name=CentOS-6.9 - Updates
baseurl=http://vault.centos.org/6.9/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.9-extras]
name=CentOS-6.9 - Extras
baseurl=http://vault.centos.org/6.9/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.9-contrib]
name=CentOS-6.9 - Contrib
baseurl=http://vault.centos.org/6.9/contrib/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
[C6.9-centosplus]
name=CentOS-6.9 - CentOSPlus
baseurl=http://vault.centos.org/6.9/centosplus/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
enabled=0
EOF
cat > /etc/yum.repos.d/epel.repo <<'EOF'
[epel]
name=Extra Packages for Enterprise Linux 6 - $basearch
baseurl=http://mirrors.cloud.tencent.com/epel/6/$basearch
#metalink=https://mirrors.fedoraproject.org/metalink?repo=epel-7&arch=$basearch
failovermethod=priority
enabled=1
gpgcheck=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6
[epel-debuginfo]
name=Extra Packages for Enterprise Linux 6 - $basearch - Debug
baseurl=http://mirrors.cloud.tencent.com/epel/6/$basearch/debug
#metalink=https://mirrors.fedoraproject.org/metalink?repo=epel-debug-7&arch=$basearch
failovermethod=priority
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6
gpgcheck=0
[epel-source]
name=Extra Packages for Enterprise Linux 6 - $basearch - Source
baseurl=http://mirrors.cloud.tencent.com/epel/6/SRPMS
#metalink=https://mirrors.fedoraproject.org/metalink?repo=epel-source-7&arch=$basearch
failovermethod=priority
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6
gpgcheck=0
EOF
cat > /etc/yum.repos.d/epel-testing.repo <<'EOF'
[epel-testing]
name=Extra Packages for Enterprise Linux 6 - Testing - $basearch
baseurl=http://mirrors.cloud.tencent.com/epel/testing/6/$basearch
#metalink=https://mirrors.fedoraproject.org/metalink?repo=testing-epel7&arch=$basearch
failovermethod=priority
enabled=0
gpgcheck=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6
[epel-testing-debuginfo]
name=Extra Packages for Enterprise Linux 6 - Testing - $basearch - Debug
baseurl=http://mirrors.cloud.tencent.com/epel/testing/6/$basearch/debug
#metalink=https://mirrors.fedoraproject.org/metalink?repo=testing-debug-epel7&arch=$basearch
failovermethod=priority
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6
gpgcheck=0
[epel-testing-source]
name=Extra Packages for Enterprise Linux 6 - Testing - $basearch - Source
baseurl=http://mirrors.cloud.tencent.com/epel/testing/6/SRPMS
#metalink=https://mirrors.fedoraproject.org/metalink?repo=testing-source-epel7&arch=$basearch
failovermethod=priority
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6
gpgcheck=0
EOF
5.清理老的YUM源缓存并重新生成YUM源和EPEL源的缓存：
yum clean all yum makecache
6.安装常用软件工具：
#安装Wget yum install -y wget #安装vim yum install -y vim #安装net-tools yum install -y net-tools #安装gcc yum -y install gcc make #安装自动补全命令工具bash-completion yum -y install bash-completion #杀死僵尸进程工具psmisc yum -y install psmisc
7.完成
上文中第四步其实也可以直通上传替换到的文件来实现。