1.含义
yum（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体包，无须繁琐地一次次下载、安装。
2.语法
yum [options] [command] [package ...]
options：可选，选项包括
-h（帮助）
-y（当安装过程提示选择全部为"yes"）
-q（不显示安装的过程）
command：要进行的操作
package操作的对象
3.命令使用格式
（1）列出所有可更新的软件清单命令
yum check-update（2）更新所有软件命令
yum update（3）仅安装指定的软件命令
yum install <package_name>（4）仅更新指定的软件命令
yum update <package_name>（5）列出所有可安裝的软件清单命令
yum list（6）删除软件包命令
yum remove <package_name>（7）查找软件包命令
yum search <keyword>（8）清除缓存命令:
# 清除缓存目录下的软件包
yum clean packages# 清除缓存目录下的 headers
yum clean headers# 清除缓存目录下旧的headers
yum clean oldheaders# 清除缓存目录下的软件包及旧的headers
yum clean
yum clean all4.示例
（1）安装 pam-devel
yum install pam-devel -ySetting up Install Process
Parsing package install arguments
Resolving Dependencies
--> Running transaction check
---> Package pam-devel.i386 0:0.99.6.2-4.el5 set to be updated
--> Processing Dependency: pam = 0.99.6.2-4.el5 for package: pam-devel
--> Running transaction check
---> Package pam.i386 0:0.99.6.2-4.el5 set to be updated
filelists.xml.gz 100% |=========================| 1.6 MB 00:05
filelists.xml.gz 100% |=========================| 138 kB 00:00
-> Finished Dependency Resolution……（2）移除 pam-devel
yum remove pam-develSetting up Remove Process
Resolving Dependencies
--> Running transaction check
---> Package pam-devel.i386 0:0.99.6.2-4.el5 set to be erased
--> Finished Dependency Resolution
Dependencies Resolved=============================================
Package Arch Version Repository Size========================================
Removing:
pam-devel i386 0.99.6.2-4.el5 installed 495 k
Transaction Summary========================
Install 0 Package(s)
Update 0 Package(s)
Remove 1 Package(s)
Is this ok [y/N]: y
Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
Erasing : pam-devel ######################### [1/1]
Removed: pam-devel.i386 0:0.99.6.2-4.el5
Complete!（3）查找以 pam 为开头的软件包
使用通配符*
yum list pam*Installed Packagespam.i386 0.99.6.2-3.27.el5 installed
pam_ccreds.i386 3-5 installed
pam_krb5.i386 2.2.14-1 installed
pam_passwdqc.i386 1.0.2-1.2.2 installed
pam_pkcs11.i386 0.5.3-23 installed
pam_smb.i386 1.1.7-7.2.1 installed
Available Packages
pam.i386 0.99.6.2-4.el5 base
pam-devel.i386 0.99.6.2-4.el5 base
pam_krb5.i386 2.2.14-10 base