小Q：温故而知新，可以为师矣；今天看的不少了，回头看几遍。

==========================快速更换国内yum源===========================

1.删除/etc/yum.repos.d目录所有的repo文件

2.下载CentOS-Base-163.repo, 放入/etc/yum.repos.d/

wget http://mirrors.163.com/.help/CentOS-Base-163.repo -O /etc/yum.repos.d/CentOS-Base-163.repo 

//说明，如果163的镜像失效，可以尝试更换为搜狐的镜像  http://mirrors.sohu.com/help/CentOS-Base-sohu.repo

3. rm -rf /var/cache/yum/*      运行yum makecache生成缓存

4.yum search softwarename       查找软件

5.yum list softwarename         列出已装软件

6.yum install softwarename      安装软件

7.yun remove softwarename      卸载软件

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CentOS-Base-163.repo源文件如下：

# 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 - 163.com

mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os

baseurl=http://mirrors.163.com/centos/$releasever/os/$basearch/

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5

#released updates 

[updates]

name=CentOS-$releasever - Updates - 163.com

mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates

baseurl=http://mirrors.163.com/centos/$releasever/updates/$basearch/

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5

#packages used/produced in the build but not released

[addons]

name=CentOS-$releasever - Addons - 163.com

mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=addons

baseurl=http://mirrors.163.com/centos/$releasever/addons/$basearch/

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5

#additional packages that may be useful

[extras]

name=CentOS-$releasever - Extras - 163.com

mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras

baseurl=http://mirrors.163.com/centos/$releasever/extras/$basearch/

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5

#additional packages that extend functionality of existing packages

[centosplus]

name=CentOS-$releasever - Plus - 163.com

mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus

baseurl=http://mirrors.163.com/centos/$releasever/centosplus/$basearch/

gpgcheck=1

enabled=0

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5

#contrib - packages by Centos Users

[contrib]

name=CentOS-$releasever - Contrib - 163.com

mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib

baseurl=http://mirrors.163.com/centos/$releasever/contrib/$basearch/

gpgcheck=1

enabled=0

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5

====================安装卸载图形界面====================

命令行模式安装图形界面

yum grouplist 检查已安装的组

yum groupinstall "X Window System"

yum groupinstall "GNOME Desktop Environment"

startx

或者init 5

就OK。

如果你的机子设置了中文模式，需要先LANG=en

重新安装了带图形界面模式的centos系统，来实验yum方式卸载图形界面

图形界面想要卸载：

yum groupremove "GNOME Desktop Environment"

yum groupremove "X Window System"

以图形界面安装的linux 卸载图形界面之后会提示错误

init: Id "x" respawning too fast: disabled for 5 minutes

解决的办法是

vi /etc/inittab

找到这段文字 把这段文字中id后面的数字改为3 id:3:initdefault 让系统以文本界面启动

找到这段文字x:5:respawn:/etc/X11/prefdm -nodaemon注释掉！