玩转 CentOS 7

[bingooyong]

CentOS 7 关闭图形界面

查看/etc/inittab如下：

# systemd uses 'targets' instead of runlevels. 
# by default, there are two main targets:
#
# multi-user.target: analogous to runlevel 3
# graphical.target: analogous to runlevel 5
#
# To view current default target, run:
# systemctl get-default
#
# To set a default target, run:
# systemctl set-default TARGET.target

新版本的CentOS 系统里使用’targets’ 取代了运行级别的概念。系统有两种默认的’targets’: 多用户.target 对应之前版本的3 运行级别； 而图形.target 对应之前的5运行级别。

查看默认的target，执行：

systemctl get-default

开机以命令模式启动，执行：

systemctl set-default multi-user.target

开机以图形界面启动，执行：

systemctl set-default graphical.target

[bingooyong]

Centos修改yum源为国内阿里源

以下为修改Centos6.5的yum源：

1. 备份原镜像文件，便于后期恢复

[root@keepmydream ~]# mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

2.下载新的CentOS-Base.repo 到/etc/yum.repos.d/

Centos5地址：

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-5.repo

Centos6地址：

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo

Centos7地址：

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

3. 清除缓存

yum clean all

4. 生成缓存

yum makecache

[bingooyong]

一键自动部署安装阿里云yum镜像源

#!/bin/bash
#一键自动部署安装阿里云yum镜像源
#Date:2020.04.17

#set -euo pipefail

#判断yum源安装是否完成，并将输出结果写入日志
install_result(){
    if [ $? -eq 0 ];then
       echo "安装 aliyun yum源成功"    
    else
        echo "安装 aliyun yum源失败"
        exit 1 
    fi
}

#检查网络情况
ping -c 1 developer.aliyun.com >/dev/null && ping -c 1 www.baidu.com >/dev/null &&
[ $? -eq 0 ] && echo "网络检测正常，正在进行下一步" || echo “网络异常，请检查当前网络情况”

#检查wget命令是否安装
wget --version >/dev/null || yum install wget -y

#备份系统yum文件

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
mv /etc/yum.repos.d/epel.repo /etc/yum.repos.d/epel.repo.backup
mv /etc/yum.repos.d/epel-testing.repo /etc/yum.repos.d/epel-testing.repo.backup

#获取当前系统型号
Centos_Version=`cat /etc/redhat-release |awk -F"[. ]+" '{print $4}'`

echo "正在为您安装Centos ${Centos_Version} 阿里云镜像源，请稍等..."

#通过wget方式下载阿里云yum源、epel源
case ${Centos_Version} in

    6)
        yum_6="wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo"
        epel_6="wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-6.repo"
        ${yum_6} && ${epel_6}
        install_result   # 调用结果判断函数
        ;;
    7)
        yum_7="wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo"
        epel_7="wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo"
        ${yum_7} && ${epel_7}
        install_result  # 调用结果判断函数
        ;;
    8)
        yum_8="wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-8.repo"
        epel_8="yum install -y https://mirrors.aliyun.com/epel/epel-release-latest-8.noarch.rpm"
        ${yum_8} && ${epel_8}
    install_result  # 调用结果判断函数
        #将repo配置中的地址替换为阿里云镜像站地址
        sed -i 's|^#baseurl=https://download.fedoraproject.org/pub|baseurl=https://mirrors.aliyun.com|' /etc/yum.repos.d/epel*
        sed -i 's|^metalink|#metalink|' /etc/yum.repos.d/epel*
        ;;
    *)

        echo "获取该系统版本信息为为:${Centos_Version}，请检查当前系统信息"
    exit 1
    ;;
esac

#yum缓存
echo "正在进行yum makecache, 请勿操作..."
yum clean all >/dev/null && yum makecache fast >>Dev_install_yum.log
if [ $? -eq 0 ];then
    echo "清除yum源或生成yum缓存成功"
else
    echo "清除yum源或生成yum缓存失败"
    echo "清除yum源或生成yum缓存失败"
fi

验证当前安装了哪些源

[root@localhost ~]# yum repolist
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.aliyun.com
 * extras: mirrors.aliyun.com
 * updates: mirrors.aliyun.com
源标识                                                                                                            源名称                                                                                                                                          状态
base/7/x86_64                                                                                                     CentOS-7 - Base - mirrors.aliyun.com                                                                                                            10,072
epel/x86_64                                                                                                       Extra Packages for Enterprise Linux 7 - x86_64                                                                                                  13,584
extras/7/x86_64                                                                                                   CentOS-7 - Extras - mirrors.aliyun.com                                                                                                             468
updates/7/x86_64                                                                                                  CentOS-7 - Updates - mirrors.aliyun.com                                                                                                          1,969
repolist: 26,093

配置阿里云epel 源

配置参考：http://mirrors.aliyun.com/help/epel

## 1、备份(如有配置其他epel源)
mv /etc/yum.repos.d/epel-testing.repo /etc/yum.repos.d/epel-testing.repo.backup

## 2、下载新repo 到/etc/yum.repos.d/
# epel(RHEL 7)
wget-O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo
# epel(RHEL 6)
wget-O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-6.repo
# epel(RHEL 5)
wget-O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-5.repo

yum clean all
yum makecache

参考： 部署阿里镜像yum源及epel源 阿里云Centos镜像源和EPEL源