腾讯云centos7.6的运维笔记——从yum的安装与更新源开始

一. 如何彻底卸载原有yum并重新安装

问题背景：常常在执行yum命令时，出现如下错误

Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfileOne of the configured repositories failed (Unknown),and yum doesn't have enough cached data to continue. At this point the onlysafe thing yum can do is fail. There are a few ways to work "fix" this:1. Contact the upstream for the repository and get them to fix the problem.2. Reconfigure the baseurl/etc. for the repository, to point to a workingupstream. This is most often useful if you are using a newerdistribution release than is supported by the repository (and thepackages for the previous distribution release still work).3. Run the command with the repository temporarily disabledyum --disablerepo=<repoid> ...4. Disable the repository permanently, so yum won't use it by default. Yumwill then just ignore the repository until you permanently enable itagain or use --enablerepo for temporary usage:yum-config-manager --disable <repoid>orsubscription-manager repos --disable=<repoid>5. Configure the failing repository to be skipped, if it is unavailable.Note that yum will try to contact the repo. when it runs most commands,so will have to try and fail each time (and thus. yum will be be muchslower). If it is a very temporary problem though, this is often a nicecompromise:yum-config-manager --save --setopt=<repoid>.skip_if_unavailable=trueCannot find a valid baseurl for repo: centos-sclo-sclo

1. 查看已经安装的yum

rpm -qa |grep yum

2. 删除yum包

rpm -qa|grep yum|xargs rpm -e --nodeps

3. 查看是否删除完毕（未找到yum包则删除完成）

rpm -qa |grep yum

4. 查看Liunx系统版本

uname -an

5. 下载yum有关的RPM包

wget https://buildlogs.cdn.centos.org/c7.00.03/python-iniparse/20140609190145/0.4-9.el7.x86_64/python-iniparse-0.4-9.el7.noarch.rpm
wget https://buildlogs.cdn.centos.org/c7.2009.00.x86_64/yum/20201001170128/3.4.3-168.el7.centos.x86_64/yum-3.4.3-168.el7.centos.noarch.rpm
wget https://buildlogs.cdn.centos.org/c7.2003.u.armhfp/yum-utils/20200512164914/1.1.31-54.el7_8.armhfp/yum-utils-1.1.31-54.el7_8.noarch.rpm
wget https://buildlogs.cdn.centos.org/c7.2003.u.armhfp/yum-utils/20200512164914/1.1.31-54.el7_8.armhfp/yum-plugin-fastestmirror-1.1.31-54.el7_8.noarch.rpm
wget https://buildlogs.cdn.centos.org/c7.00.03/yum-metadata-parser/20140609201710/1.1.4-10.el7.x86_64/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm

6. 安装下载好的yum有关的RPM包

rpm -ivh python-iniparse-0.4-9.el7.noarch.rpm --force --nodeps
rpm -ivh yum-* --force --nodeps
rpm -qa |grep yum

7. 查看是否安装完成

yum makecache

二. 如何更新yum源

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

三. 如何安装图形化界面并最终通过VNC登录

3.1 安装图形化界面

yum groupinstall "GNOME Desktop" "Graphical Administration Tools" -y
ln -sf /lib/systemd/system/runlevel5.target /etc/systemd/system/default.target
reboot

3.2 通过VNC登录

四、如何安装google-chrome

curl -s https://packagecloud.io/install/repositories/ivan/centos/script.rpm.sh | sudo bash
sudo yum install google-chrome-stable-53.0.2785.143-1.x86_64

参考文献

1. Linux：CentOS 7 安装yum
2. CentOS 7 更换 阿里云/清华大学 yum 软件源
3. 搭建 CentOS 可视化界面
   
4. google-chrome-stable-53.0.2785.143-1.x86_64.rpm