Linux系统之前端程序包管理器-yum
【前言】
当我们使用rpm命令安装程序时，时常会因为程序包之间的依赖关系而焦头烂额，使得很多程序的安装过程复杂而费力，那有没有一种工具可以帮我们解决这个问题呢？当然有啦！这就是我们今天的重点yum，让我们一块来学习总结下吧！
【什么是yum】
yum（全称为 Yellow dog Updater, Modified）是一个在Fedora和RedHat以及SUSE中的Shell前端软件包管理器。基於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体包，无须繁琐地一次次下载、安装。yum提供了查找、安装、删除某一个、一组甚至全部软件包的命令，而且命令简洁而又好记。
【yum的工作机制】
yum 的关键之处是要有可靠的yum仓库（yum repository），它可以是http 或ftp 站点，也可以是本地软件池，其必须包含两类数据：
1、数据：也就是各个rpm包;
2、元数据：其包含了rpm 包的各种信息，包括包名、描述，功能，提供的文件，依赖关系、包分组信息等。正是通过收集汇总这些元数据 并加以分析，才能自动化地完成余下的任务。在各版本系统下其的存储格式为：centos5: *.xml； centos6,7: *.sqlite
其实从架构的角度来看，yum的工作机制为C/S架构，如下图所示：
【yum的使用机制】
1、确保有yum repo(yum仓库的配置文件)可用；rpm包的文件服务器，repodata目录所在父目录就是一个可用仓库。
2、yum客户端需要指供repo配置文件，指明yum仓库访问路径及各种属性信息。有两种配置方法：
法一：修改主配置文件（中心配置文件）：/etc/yum.conf；
法二：在/etc/yum.repos.d/下创建或修改*.repo文件（存储一个或几个相关仓库的配置信息）。
在.repo文件定义一个yum repo指向的格式：
[REPOID] #定义软件源的名称，该名称是可以自定义，同时在该服务器上所有repo文件中是唯一的。注意[]中不能有空格；
name=Some name for this repository #定义软件仓库的名称，支持像$releasever 、$basearch这样的变量；注意=两边不能有空格；
baseurl=url://server/path/to/repository #指定真正的仓库所在地，可以给定多个，下面的URL不能顶格书写，URL中也支持$releasever 、$basearch这样的变量；
http://mirrors.sohu.com/centos/$releasever/os/$basearch
enabled={0|1} #配置此仓库是否启用，默认为1生效；
gpgcheck={0|1} #配置是否验证安装包，0为不进行验证，1为进行验证；
gpgkey=URL #指定用于验证的秘钥文件
cost={1..n} #默认为1000，指定访问此仓库的开销（在客户端指定）
补充说明：
1、$basearch: 系统基本架构，如i686，i586等的基本架构为i386；
$releasever: 程序的版本，对yum而言指的是redhat-release版本；只替换为主版本号，如RedHat 6.5，则替换为6;
2 、baseurl种url支持的协议有：http://、ftp://、nfs://、file://、 rsync://；当需要指定多个URL且不想通过baseurl来指定时， 我们可以把多个URL存放在一个文件里，通过mirrorlist=存放URL的文件来指定yum仓库。
3、一个.repo文件可以定义多个yum仓库。
[root@CentOS6 yum.repos.d]# ls /etc/yum.repos.d/ CentOS-Base.repo CentOS-Debuginfo.repo CentOS-Media.repo CentOS-Vault.repo [root@CentOS6 mnt]# cat /etc/yum.repos.d/CentOS-Media.repo [c6-media] name=CentOS-$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 [root@CentOS6 yum.repos.d]#
【yum客户端命令的使用】
1、列出所有可用repo
yum repolist {enabled|disabled|all} enabled:可用的；disabled:不可用的；all：所有的 ，不带参数默认为列出可用的
[root@CentOS6 yum.repos.d]# yum repolist enabled Loaded plugins: fastestmirror, refresh-packagekit, security Loading mirror speeds from cached hostfile repo id repo name status c6-cd CentOS-6 - cd 4,802 repolist: 4,802 [root@CentOS6 yum.repos.d]# yum repolist disabled Loaded plugins: fastestmirror, refresh-packagekit, security repo id repo name c6-media CentOS-6 - Media repolist: 0 [root@CentOS6 yum.repos.d]# yum repolist all Loaded plugins: fastestmirror, refresh-packagekit, security Loading mirror speeds from cached hostfile repo id repo name status c6-cd CentOS-6 - cd enabled: 4,802 c6-media CentOS-6 - Media disabled repolist: 4,802 [root@CentOS6 yum.repos.d]#
2、列出rpm包
yum list {all|installed|available} all:所有的；installed: 已安装的；available:可以安装的;默认为列出所有的
yum list KEYWORD* 支持使用文件名通配，来获取含有关键字的rpm包
[root@CentOS6 yum.repos.d]# yum list http* #列出所有以http开头的rpm包 Loaded plugins: fastestmirror, refresh-packagekit, security Loading mirror speeds from cached hostfile Installed Packages #下面为已经安装的包 httpd-tools.i686 2.2.15-29.el6.centos @anaconda-CentOS-201311271240.i386/6.5 Available Packages #下面为可以安装的包 httpd.i686 2.2.15-29.el6.centos c6-cd httpd-devel.i686 2.2.15-29.el6.centos c6-cd httpd-manual.noarch 2.2.15-29.el6.centos c6-cd
3、列出包的描述信息（无论包有没有安装都可以列出）
yum info package_name
[root@CentOS6 yum.repos.d]# yum info httpd #列出http包的描述信息 Loaded plugins: fastestmirror, refresh-packagekit, security Loading mirror speeds from cached hostfile Available Packages Name : httpd Arch : i686 Version : 2.2.15 Release : 29.el6.centos Size : 828 k Repo : c6-cd Summary : Apache HTTP Server URL : http://httpd.apache.org/ License : ASL 2.0 Description : The Apache HTTP Server is a powerful, efficient, and extensible : web server.
4、列出所有的包组信息
yum grouplist
[root@CentOS6 yum.repos.d]# yum grouplist Loaded plugins: fastestmirror, refresh-packagekit, security Setting up Group Process Loading mirror speeds from cached hostfile c6-cd/group_gz | 212 kB 00:00 ... Installed Groups: #已安装的包组 Additional Development Base ... Installed Language Groups: #已安装的语言包组 Arabic Support [ar] ... Available Groups: #可安装的包组 Backup Client ... Available Language Groups: #可安装的语言包组 Afrikaans Support [af] ... Done
5、显示包组的信息：列出组中包含的程序包列表（如果包组名中含有空格必须用“”引起来）
yum groupinfo "GROUP NAME"
[root@CentOS6 yum.repos.d]# yum groupinfo "Development Tools" #显示开发工具包组的信息 Loaded plugins: fastestmirror, refresh-packagekit, security Setting up Group Process Loading mirror speeds from cached hostfile Group: Development tools Description: A basic development environment. Mandatory Packages: autoconf ... Default Packages: byacc ... Optional Packages: ElectricFence ...
CentOS6 跟开发相关的包组有： Development Tools、Server Platform Development、 Desktop Platform Development
6、清理缓存
yum clean {all|packages|metadata|expire-cache|rpmdb|plugins}
yum clean all 清除缓存目录（/var/cache/yum）下的软件包以及旧的元数据
[root@CentOS6 yum.repos.d]# yum clean all Loaded plugins: fastestmirror, refresh-packagekit, security Cleaning repos: c6-cd Cleaning up Everything Cleaning up list of fastest mirrors
7、安装程序包
yum install package_name {-y} -y:自动回答为yes,执行过程中无需等待用户再次输入
[root@CentOS6 yum.repos.d]# yum install httpd Loaded plugins: fastestmirror, refresh-packagekit, security Determining fastest mirrors c6-cd | 4.0 kB 00:00 ... c6-cd/primary_db | 3.4 MB 00:00 ... Setting up Install Process Resolving Dependencies --> Running transaction check ---> Package httpd.i686 0:2.2.15-29.el6.centos will be installed --> Finished Dependency Resolution Dependencies Resolved ================================================================================= Package Arch Version Repository Size ================================================================================= Installing: httpd i686 2.2.15-29.el6.centos c6-cd 828 k Transaction Summary ================================================================================ Install 1 Package(s) Total download size: 828 k Installed size: 2.8 M Is this ok [y/N]: y Downloading Packages: Running rpm_check_debug Running Transaction Test Transaction Test Succeeded Running Transaction Warning: RPMDB altered outside of yum. ** Found 1 pre-existing rpmdb problem(s), ‘yum check‘ output follows: gnome-user-share-2.28.2-3.el6.i686 has missing requires of httpd >= (‘0‘, ‘2.2.0‘, None) Installing : httpd-2.2.15-29.el6.centos.i686 1/1 Verifying : httpd-2.2.15-29.el6.centos.i686 1/1 Installed: httpd.i686 0:2.2.15-29.el6.centos Complete!
重新安装：
yum reinstall package_name
8、升级
yum check-update: 检查可用的升级包
yum update package_name 升级，当不指定版本时，默认升级到最新版本
yum downgrade package_name 降价到指定版本
9、卸载（卸载时为解决该包安装的依赖关系而安装的包也会一同卸载）
yum remove|erase package_name {-y} -y:自动回答为yes,执行过程中无需等待用户再次输入
10、查询某文件是由哪个包安装生成的
yum whatprovides|provides /path/to/somefile
[root@CentOS6 yum.repos.d]# yum provides /usr/bin/zip #查询出zip文件是由那个包安装生成； Loaded plugins: fastestmirror, refresh-packagekit, security Loading mirror speeds from cached hostfile zip-3.0-1.el6.i686 : A file compression and packaging utility compatible with PKZIP Repo : c6-cd Matched from: Filename : /usr/bin/zip zip-3.0-1.el6.i686 : A file compression and packaging utility compatible with PKZIP Repo : installed Matched from: Other : Provides-match: /usr/bin/zip
11、安装包组
yum groupinstall "GROUP NAME"
12、卸载包组
yum groupremove "GROUP NAME"
【自建yum仓库】
下面通过自建一个http服务器的yum仓库为例说明：
第一步：安装httpd程序并启动服务；
yum -y install httpd
service httpd start
chkconfig httpd on
[root@CentOS6 yum.repos.d]# yum -y install httpd Loaded plugins: fastestmirror, refresh-packagekit, security Loading mirror speeds from cached hostfile Setting up Install Process Resolving Dependencies --> Running transaction check ---> Package httpd.i686 0:2.2.15-29.el6.centos will be installed --> Finished Dependency Resolution Dependencies Resolved ================================================================================ Package Arch Version Repository Size ================================================================================ Installing: httpd i686 2.2.15-29.el6.centos c6-cd 828 k Transaction Summary ================================================================================ Install 1 Package(s) Total download size: 828 k Installed size: 2.8 M Downloading Packages: Running rpm_check_debug Running Transaction Test Transaction Test Succeeded Running Transaction Installing : httpd-2.2.15-29.el6.centos.i686 1/1 Verifying : httpd-2.2.15-29.el6.centos.i686 1/1 Installed: httpd.i686 0:2.2.15-29.el6.centos Complete! [root@CentOS6 yum.repos.d]# service httpd start Starting httpd: [ OK ] [root@CentOS6 yum.repos.d]# chkconfig httpd on [root@CentOS6 yum.repos.d]# chkconfig |grep httpd httpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off
第二步：创建子目录，存放某相关的所有rpm包，httpd的文档根目录为/var/www/html；为仓库生成元数据文件（使用createrepo），以使能够作为仓库使用。
[root@CentOS6 html]# cd /var/www/html [root@CentOS6 html]# mkdir test #创建test目录用来测试； [root@CentOS6 html]# cp /mnt/cd/Packages/zsh-4.3.10-7.el6.i686.rpm ./test #复制zsh这个安装包到test目录； [root@CentOS6 Packages]# yum install createrepo #安装createrepo，如提前已安装则不用再装； Loaded plugins: fastestmirror, refresh-packagekit, security Loading mirror speeds from cached hostfile Setting up Install Process Resolving Dependencies --> Running transaction check ---> Package createrepo.noarch 0:0.9.9-18.el6 will be installed --> Processing Dependency: python-deltarpm for package: createrepo-0.9.9-18.el6.noarch --> Running transaction check ---> Package python-deltarpm.i686 0:3.5-0.5.20090913git.el6 will be installed --> Processing Dependency: deltarpm = 3.5-0.5.20090913git.el6 for package: python-deltarpm-3.5-0.5.20090913git.el6.i686 --> Running transaction check ---> Package deltarpm.i686 0:3.5-0.5.20090913git.el6 will be installed --> Finished Dependency Resolution Dependencies Resolved ====================================================================== Package Arch Version Repository Size ====================================================================== Installing: createrepo noarch 0.9.9-18.el6 c6-cd 94 k Installing for dependencies: deltarpm i686 3.5-0.5.20090913git.el6 c6-cd 73 k python-deltarpm i686 3.5-0.5.20090913git.el6 c6-cd 27 k Transaction Summary ========================================================================== Install 3 Package(s) Total download size: 195 k Installed size: 522 k Is this ok [y/N]: y Downloading Packages: ----------------------------------------------------------------------------------------- Total 3.3 MB/s | 195 kB 00:00 Running rpm_check_debug Running Transaction Test Transaction Test Succeeded Running Transaction Installing : deltarpm-3.5-0.5.20090913git.el6.i686 1/3 Installing : python-deltarpm-3.5-0.5.20090913git.el6.i686 2/3 Installing : createrepo-0.9.9-18.el6.noarch 3/3 Verifying : createrepo-0.9.9-18.el6.noarch 1/3 Verifying : python-deltarpm-3.5-0.5.20090913git.el6.i686 2/3 Verifying : deltarpm-3.5-0.5.20090913git.el6.i686 3/3 Installed: createrepo.noarch 0:0.9.9-18.el6 Dependency Installed: deltarpm.i686 0:3.5-0.5.20090913git.el6 python-deltarpm.i686 0:3.5-0.5.20090913git.el6 Complete! #createrepo安装完成 [root@CentOS6 Packages]# createrepo /var/www/html/test/ #创建元数据文件； Spawning worker 0 with 1 pkgs Workers Finished Gathering worker results Saving Primary metadata Saving file lists metadata Saving other metadata Generating sqlite DBs Sqlite DBs complete [root@CentOS6 Packages]# ls /var/www/html/test/ repodata zsh-4.3.10-7.el6.i686.rpm #repodata即为刚刚创建出来存放元数据文件的目录； [root@CentOS6 test]# ls /var/www/html/test/repodata/ #查看repodata下的元数据文件； 105b962a2624ebddd589ec03c1e4fdcd7a3511ea1e47fd80eeda364b41d48cdd-primary.sqlite.bz2 7762e79a7341d1b6a929e893fd732302dd27499742abf4549130601465760426-filelists.xml.gz 78f72a947bd046641a5ea0574872212cfe829f1525ff74f1d13f4da3c4d73cde-filelists.sqlite.bz2 7e8d7b7938dbd28a823ebe27420f3c2d088f9a1933f37319e925295e24417009-other.sqlite.bz2 885867e505b55bc3f09fb4eec3bc7cf8a5352cce29c307e7b37afaa38e3d33cc-primary.xml.gz e0eb2191ed5de3b3975bbb005a00e07a044d5724b87373d4a6cdf399ff99bf3f-other.xml.gz #通过以上几步一个简单的yum仓库就搭建好了！
第三步：配置yum客户端使用此仓库即可；
[root@CentOS6 yum.repos.d]# vim test.repo #编辑指向yum库的repo文件 [c6-test] name=CentOS-$releasever - test baseurl=file:///var/www/html/test gpgcheck=0 #此处只为实验，没有复制密钥，到yum库中，所以不启用校验； enabled=1 #启用 [root@CentOS6 yum.repos.d]# yum clean all #清除缓存； Loaded plugins: fastestmirror, refresh-packagekit, security Cleaning repos: c6-test Cleaning up Everything Cleaning up list of fastest mirrors [root@CentOS6 yum.repos.d]# yum repolist #显示可用的repo; Loaded plugins: fastestmirror, refresh-packagekit, security Determining fastest mirrors c6-test | 2.9 kB 00:00 ... c6-test/primary_db | 3.2 kB 00:00 ... repo id repo name status c6-test CentOS-6 - test 1 repolist: 1 [root@CentOS6 yum.repos.d]# yum -y install zsh #安装zsh； Loaded plugins: fastestmirror, refresh-packagekit, security Loading mirror speeds from cached hostfile Setting up Install Process Resolving Dependencies --> Running transaction check ---> Package zsh.i686 0:4.3.10-7.el6 will be installed --> Finished Dependency Resolution Dependencies Resolved ========================================================================== Package Arch Version Repository Size ========================================================================== Installing: zsh i686 4.3.10-7.el6 c6-test 2.1 M Transaction Summary ========================================================================== Install 1 Package(s) Total download size: 2.1 M Installed size: 4.6 M Downloading Packages: Running rpm_check_debug Running Transaction Test Transaction Test Succeeded Running Transaction Installing : zsh-4.3.10-7.el6.i686 1/1 Verifying : zsh-4.3.10-7.el6.i686 1/1 Installed: zsh.i686 0:4.3.10-7.el6 Complete! #安装成功！实验完成！
好啦！可能描写的比较啰嗦，如有总结说明不妥的地方，还请各位见谅！谢谢！
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