查看“Yum”的源代码

=== 简介 ===
Yum（全称为 Yellow dog Updater, Modified）是一个在 '''<big>Fedora</big>''' 和 '''<big>RedHat</big>''' 以及 <big>'''CentOS'''</big> 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。



=== 显示配置的软件存储库 ===
<syntaxhighlight lang="shell-session">
[root@localhost docker_zk]# yum repolist
Loaded plugins: fastestmirror
Repodata is over 2 weeks old. Install yum-cron? Or run: yum makecache fast
Loading mirror speeds from cached hostfile
 * base: mirrors.bfsu.edu.cn
 * extras: mirrors.huaweicloud.com
 * updates: mirrors.bfsu.edu.cn
repo id                                            repo name                                  status
!base/7/x86_64                                     CentOS-7 - Base                            10,072
!extras/7/x86_64                                   CentOS-7 - Extras                             500
!mysql-connectors-community/x86_64                 MySQL Connectors Community                    221
!mysql-tools-community/x86_64                      MySQL Tools Community                         135
!mysql56-community/x86_64                          MySQL 5.6 Community Server                    581
!updates/7/x86_64                                  CentOS-7 - Updates                          2,943
repolist: 14,452
[root@localhost docker_zk]#
</syntaxhighlight>



=== 查看已安装 ===
<syntaxhighlight lang="shell-session">
[root@bogon docker_zk]# yum list installed
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.bfsu.edu.cn
 * extras: mirrors.huaweicloud.com
 * updates: mirrors.bfsu.edu.cn
Installed Packages
NetworkManager.x86_64                                                        1:1.18.8-2.el7_9                                                        @updates          
NetworkManager-libnm.x86_64                                                  1:1.18.8-2.el7_9                                                        @updates 
......
[root@bogon docker_zk]#
</syntaxhighlight>



=== 确认是否安装 ===
<syntaxhighlight lang="shell-session">
[root@localhost docker_zk]# yum list installed|grep wget
Repodata is over 2 weeks old. Install yum-cron? Or run: yum makecache fast
wget.x86_64                          1.14-18.el7_6.1                @base
[root@localhost docker_zk]# yum list installed|grep yum-utils
Repodata is over 2 weeks old. Install yum-cron? Or run: yum makecache fast
[root@localhost docker_zk]#
</syntaxhighlight>



=== 安装 yum-utils ===
yum-utils 包含可以添加 yum 镜像的 '''<big>yum-config-manager</big>'''<syntaxhighlight lang="shell-session">
[root@localhost docker_zk]# yum install -y yum-utils
......
[root@localhost docker_zk]# yum list installed|grep yum-utils
yum-utils.noarch                     1.1.31-54.el7_8                @base
[root@localhost docker_zk]#

</syntaxhighlight>



=== yum 添加镜像 ===
这里以 docker 镜像为例<syntaxhighlight lang="shell-session">
[root@localhost docker_zk]# yum-config-manager --add-repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
Loaded plugins: fastestmirror
adding repo from: https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
grabbing file https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo to /etc/yum.repos.d/docker-ce.repo
repo saved to /etc/yum.repos.d/docker-ce.repo
[root@localhost docker_zk]#
</syntaxhighlight>



=== yum makecache ===
添加镜像或缓存过期时需要进行此操作

用于下载当前启用的 yum 存储库的所有元数据并使其可用。

如果参数“fast”被传递，那么我们只是尝试确保 repos 是最新的（很像“yum clean expire-cache”）。<syntaxhighlight lang="shell-session">
[root@localhost docker_zk]# yum makecache fast
 ...
[root@localhost docker_zk]#
</syntaxhighlight>



=== 安装 epel-release ===
EPEL（Extra Packages for Enterprise Linux）是基于 Fedora 的一个项目，为“红帽系”的操作系统提供额外的软件包，适用于 RHEL、CentOS 和 Scientific Linux.

在 CentOS 下使用 yum 在安装包的时后往往会发生找不到 rpm 的情况，官方的 rpm repository 提供的 rpm 包也不够丰富，很多时候需要自己编译很痛苦，而 EPEL 恰恰可以解决这两方面的问题。

EPEL 的全称叫 Extra Packages for Enterprise Linux 。

EPEL是由 Fedora 社区打造，为 RHEL 及衍生发行版如 CentOS、Scientific Linux 等提供高质量软件包的项目。

装上了 EPEL之后，就相当于添加了一个第三方源。<syntaxhighlight lang="shell-session">
[root@bogon docker_zk]# yum list installed|grep epel-release
[root@bogon docker_zk]# yum list |grep epel-release
epel-release.noarch                       7-11                         extras   
[root@bogon docker_zk]# yum repolist
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.bfsu.edu.cn
 * extras: mirrors.huaweicloud.com
 * updates: mirrors.bfsu.edu.cn
repo id                                                                                                               repo name                                                                                                       status
base/7/x86_64                                                                                                         CentOS-7 - Base                                                                                                 10,072
docker-ce-stable/7/x86_64                                                                                             Docker CE Stable - x86_64                                                                                          164
extras/7/x86_64                                                                                                       CentOS-7 - Extras                                                                                                  512
mysql-connectors-community/x86_64                                                                                     MySQL Connectors Community                                                                                         199
mysql-tools-community/x86_64                                                                                          MySQL Tools Community                                                                                               92
mysql56-community/x86_64                                                                                              MySQL 5.6 Community Server                                                                                         581
updates/7/x86_64                                                                                                      CentOS-7 - Updates                                                                                               4,135
repolist: 15,755
[root@bogon docker_zk]# yum -y install epel-release
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.bfsu.edu.cn
 * extras: mirrors.huaweicloud.com
 * updates: mirrors.bfsu.edu.cn
Resolving Dependencies
--> Running transaction check
---> Package epel-release.noarch 0:7-11 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

============================================================================================================================================================================================================================================
 Package                                                       Arch                                                    Version                                                Repository                                               Size
============================================================================================================================================================================================================================================
Installing:
 epel-release                                                  noarch                                                  7-11                                                   extras                                                   15 k

Transaction Summary
============================================================================================================================================================================================================================================
Install  1 Package

Total download size: 15 k
Installed size: 24 k
Downloading packages:
epel-release-7-11.noarch.rpm                                                                                                                                                                                         |  15 kB  00:00:00     
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Installing : epel-release-7-11.noarch                                                                                                                                                                                                 1/1 
  Verifying  : epel-release-7-11.noarch                                                                                                                                                                                                 1/1 

Installed:
  epel-release.noarch 0:7-11                                                                                                                                                                                                                

Complete!
[root@bogon docker_zk]# yum list installed|grep epel-release
epel-release.noarch             7-11                           @extras          
[root@bogon docker_zk]# yum repolist
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
epel/x86_64/metalink                                                                                                                                                                                                 | 6.5 kB  00:00:00     
 * base: mirrors.bfsu.edu.cn
 * epel: mirrors.bfsu.edu.cn
 * extras: mirrors.huaweicloud.com
 * updates: mirrors.bfsu.edu.cn
epel                                                                                                                                                                                                                 | 4.7 kB  00:00:00     
(1/3): epel/x86_64/updateinfo                                                                                                                                                                                        | 1.0 MB  00:00:00     
(2/3): epel/x86_64/group_gz                                                                                                                                                                                          |  97 kB  00:00:00     
(3/3): epel/x86_64/primary_db                                                                                                                                                                                        | 7.0 MB  00:00:00     
repo id                                                                                                     repo name                                                                                                                 status
base/7/x86_64                                                                                               CentOS-7 - Base                                                                                                           10,072
docker-ce-stable/7/x86_64                                                                                   Docker CE Stable - x86_64                                                                                                    164
epel/x86_64                                                                                                 Extra Packages for Enterprise Linux 7 - x86_64                                                                            13,758
extras/7/x86_64                                                                                             CentOS-7 - Extras                                                                                                            512
mysql-connectors-community/x86_64                                                                           MySQL Connectors Community                                                                                                   199
mysql-tools-community/x86_64                                                                                MySQL Tools Community                                                                                                         92
mysql56-community/x86_64                                                                                    MySQL 5.6 Community Server                                                                                                   581
updates/7/x86_64                                                                                            CentOS-7 - Updates                                                                                                         4,135
repolist: 29,513
[root@bogon docker_zk]# 
</syntaxhighlight>