yum命令解析
Yum配置文件位于/etc/yum.conf和/etc/yum.repos.d/CentOS-Base.repo目录下使用yum时注意：必须使用root身份来执行yum；yum配置文件内的镜像站点必须能与自己进行网络连接；镜像站点越近，带宽越大越好，方便下载。[root@localhost ~]# yum [options] COMMAND 软件List of Commands：install：Install a package or packages on your systemupdate：Update a package or packages on your systemremove：移出某个软件，后跟软件名称search：Search package details for the given string 搜索某个软件或重要关键字list：List a package or groups of packages列出yum所管理的软件名称与版本，类似于rpm –qainfo：Display details about a package or group of packages，类似于rpm –qaiclean：Remove cached data 下载文件被放置在/var/cache/yum中，可以使用clean清除。check-update：Check for available package updatesGroupinfo：Display details about a package groupgroupinstall Install the packages in a group on your systemgrouplist：List available package groupsgroupremove：Remove the packages in a group from your systemgroupupdate：升级整个软件群组help：Display a helpful usage messageDeplist：List a package's dependencies 列出软件包的依赖关系，在使用本地源软件包进行安装时，可以查看依赖关系Downgrade：downgrade a packageErase：Remove a package or packages from your systemlocalinstall：Install a local RPM安装本地的rpm软件包makecache：Generate the metadata cache 生成数据缓存provides：Find what package provides the given value 找到包提供的给定值reinstall：reinstall a package 重装软件包repolist：Display the configured software repositoriesresolvedep：Determine which package provides the given dependencyshell：Run an interactive yum shellupgrade：Update packages taking obsoletes into accountoptions -y：answer yes for all questions当yum询问用户意见时，主动回答yes不需由键盘输入-installroot=[path]：set install root安装在其他的路径，而不再当前目录树的架构中-h --help：show this help message and exit -t --tolerant：be tolerant of errors -C：run entirely from cache, don't update cache -c：[config file]config file location -R [minutes] maximum command wait time -d [debug level] debugging output level-showduplicates show duplicates, in repos, in list/search commands -e [error level] error output level -q, --quiet quiet operation -v, --verbose verbose operation-version show Yum version and exit-enablerepo=[repo] enable one or more repositories (wildcards allowed)-disablerepo=[repo] disable one or more repositories (wildcards allowed)-x[package], --exclude=[package]exclude package(s) by name or glob-disableexcludes=[repo]disable exclude from main, for a repo or for everything-obsoletes：enable obsoletes processing during updates-noplugins：disable Yum plugins-nogpgcheck：disable gpg signature checking-disableplugin=[plugin] disable plugins by name-enableplugin=[plugin] enable plugins by name-skip-broken：skip packages with depsolving problems-color=COLOR： control whether color is used[root@localhost ~]# yum search gcc 查找主机上是否有gcc的相关软件，如果有，就会陈列出来。[root@localhost ~]# yum info gcc 列出已安装的yum所管理的软件名称与版本……………………………………………………………………Name：gccArch：i386Version： 4.1.2Release： 48.el5Size：9.6 MRepo：installedSummary：各类编译器（C、C++、Objective-C、Java, ...）URL：http://gcc.gnu.orgLicense：GPLDescription：The gcc package contains the GNU Compiler Collection version 4.1.You'll need this package in order to compile c code……………………………………………………………………显示该软件版本名称，数据大小，软件出处等信息。需要注意summary和description的信息可以依据yum search 软件名查找此软件的信息，yum list软件名 列出此软件的版本和名称，决定是否安装此软件。安装之前使用rpm –q 软件名，查看此软件是否安装，如没有安装，使用yum install 软件名 进行安装使用yum可以主动处理好依赖关系，下载好的软件一般都放置在/var/cache/yum中，可以清除以节省磁盘空间。[root@localhost ~]# yum clean packages #清除下载的软件包[root@localhost ~]# yum -y update #手动系统更新
