yum简介
Yum(全称为 Yellow dog Updater, Modified)是一个在Fedora和RedHat以及CentOS中的Shell前端软件包管理器。基于RPM包管理，能够从指定的服务器自动下载RPM包并且安装，可以自动处理依赖性关系，并且一次安装所有依赖的软件包，无须繁琐地一次次下载、安装。
借助于YUM软件仓库，可以完成安装、卸载、自动升级rpm软件包等任务，能够自动查找并解决rpm包之间的依赖关系，而无需管理员，手工去安装每个rpm包，使管理员在维护大量Linux服务器时更加轻松自如。特别是拥有大量Linux主机的本地网络中，构建一台源服务器可以大大缓解软件安装、升级等对lnterner的依赖。
yum服务器搭建
yum服务器概述
yum软件仓库通常借助HTTP或FTP协议来进行发布，这样可以面向网络中的所有客户机提供软件源服务。为了便于客户机查询软件包，获取依赖关系等信息，在软件仓库中需要提供仓库数据(Repodata)，其中收集了目录下所有rpm包的头部信息。
准备网络安装源(服务器端)
(1)准备软件仓库目录
光盘中的软件包拷贝CentOS6.5第一张光盘内容到本地FTP服务器匿名访问用户的根目录下
[root@localhost ~]# cd /var/ftp/
[root@localhost ftp]# mkdir centos6
[root@localhost ftp]# cp -rf /media/CentOS_6.5_Final/* /var/ftp/centos6/ &
[1] 45717
[root@localhost ftp]# jobs
[1]+ Done cp -i -rf /media/CentOS_6.5_Final/* /var/ftp/centos6/
[root@localhost ksh]# cp /media/CentOS_6.5_Final/Packages/ksh-20120801-10.el6.x86_64.rpm /var/ftp/ksh/
[root@localhost ksh]# cp /media/CentOS_6.5_Final/Packages/mksh-39-7.el6_4.1.x86_64.rpm /var/ftp/ksh/
[root@localhost ksh]# ls
ksh-20120801-10.el6.x86_64.rpm mksh-39-7.el6_4.1.x86_64.rpm
未安装createrepo包需要先安装
[root@localhost ksh]# yum -y install createrepo
[root@localhost ksh]# createrepo -v ./
Spawning worker 0 with 2 pkgs
Worker 0: reading ksh-20120801-10.el6.x86_64.rpm
Worker 0: reading mksh-39-7.el6_4.1.x86_64.rpm
Workers Finished
Gathering worker results
Saving Primary metadata
Saving file lists metadata
Saving other metadata
Generating sqlite DBs
Starting other db creation: Thu May 31 18:20:51 2018
Ending other db creation: Thu May 31 18:20:51 2018
Starting filelists db creation: Thu May 31 18:20:51 2018
Ending filelists db creation: Thu May 31 18:20:51 2018
Starting primary db creation: Thu May 31 18:20:51 2018
Ending primary db creation: Thu May 31 18:20:51 2018
Sqlite DBs complete
[root@localhost ksh]# ls
ksh-20120801-10.el6.x86_64.rpm mksh-39-7.el6_4.1.x86_64.rpm repodata
安装并启动vsftpd服务(详见FTP服务内容)
[root@localhost ksh]# service vsftpd restart
关闭 vsftpd： [确定]
为 vsftpd 启动 vsftpd： [确定]
[root@localhost ksh]# chkconfig vsftpd on
[root@localhost ksh]# chkconfig vsftpd --list
vsftpd 0:关闭 1:关闭 2:启用 3:启用 4:启用 5:启用 6:关闭
配置yum软件仓库位置(客户机端)
典型仓库配置
内网YUM源
[root@n2 ~]# cd /etc/yum.repos.d/
[root@n2 yum.repos.d]# ls
CentOS-Base.repo CentOS-Debuginfo.repo CentOS-Media.repo CentOS-Vault.repo
[root@n2 yum.repos.d]# mkdir bak
[root@n2 yum.repos.d]# mv *o ./bak/
[root@n2 yum.repos.d]# ls
bak
[root@n2 yum.repos.d]# vim amber.repo
[yum]
name=centos 6.5
baseurl=ftp://192.168.28.128/centos6/
gpgcheck=0
enabled=1
[ksh]
name=ksh
baseurl=ftp://192.168.28.128/ksh/
gpgcheck=0
enabled=1
~
[root@n2 ~]# yum -y clean all
Loaded plugins: fastestmirror, refresh-packagekit, security
Cleaning repos: ksh yum
Cleaning up Everything
Cleaning up list of fastest mirrors
[root@n2 ~]# yum makecache
Loaded plugins: fastestmirror, refresh-packagekit, security
Determining fastest mirrors
ksh | 2.9 kB 00:00
ksh/filelists_db | 1.1 kB 00:00
ksh/primary_db | 3.3 kB 00:00
ksh/other_db | 2.2 kB 00:00
yum | 4.0 kB 00:00
yum/group_gz | 220 kB 00:00
yum/filelists_db | 5.8 MB 00:00
yum/primary_db | 4.4 MB 00:00
yum/other_db | 2.7 MB 00:00
Metadata Cache Created
查看yum缓存是否生成
[root@n2 ~]# ls /var/cache/yum/x86_64/6/
base extras ksh timedhosts.txt updates yum
[root@n2 ~]# ls /var/cache/yum/x86_64/6/yum/
0dafccfdbf892f02acca8267ade4bdcee7280a682e65dc7e29145f3341fd7a8c-primary.sqlite
594d4bb4a79ed01d66635adbcf76c45ca4a85b30fc3e3c3c28316e64f0a83f21-filelists.sqlite
ca525c73086186bfcb81ad9edd45796026dac7e4e50524e0f2daf901532aaf66-c6-x86_64-comps.xml.gz
cachecookie
fdd542ef36b0cde54ee0521fae90b98911db06483163aa1c049995b6d109349b-other.sqlite
gen
packages
repomd.xml
[root@n2 ~]# ls /var/cache/yum/x86_64/6/ksh
046862454d1aa798eb72c70668a54e25905c276a613fd0cc15abdf13fc20d6de-filelists.sqlite
38c945c0799d8cfb481c6145b8c227b1f2ef91100f3b7bc8cad97645594f4643-primary.sqlite
cachecookie
fe7ae063ad2b6e2c4bcdbc676581ac33eb74c0645132fb0c4bac78f24300ffb5-other.sqlite
packages
repomd.xml
测试
[root@n2 ~]# yum -y install dhcp
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package dhcp.x86_64 12:4.1.1-38.P1.el6.centos will be installed
--> Finished Dependency Resolution
Dependencies Resolved
========================================================================================================================================================
Package Arch Version Repository Size
========================================================================================================================================================
Installing:
dhcp x86_64 12:4.1.1-38.P1.el6.centos yum 817 k
Transaction Summary
========================================================================================================================================================
Install 1 Package(s)
Total download size: 817 k
Installed size: 1.9 M
Downloading Packages:
dhcp-4.1.1-38.P1.el6.centos.x86_64.rpm | 817 kB 00:00
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Warning: RPMDB altered outside of yum.
Installing : 12:dhcp-4.1.1-38.P1.el6.centos.x86_64 1/1
Verifying : 12:dhcp-4.1.1-38.P1.el6.centos.x86_64 1/1
Installed:
dhcp.x86_64 12:4.1.1-38.P1.el6.centos
Complete!
注意;因为ksh包在光盘中存在，所以需先修改repo文件后重建yum缓存再进行安装测试，否则安装的是光盘中的包。