???????????information??
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????yum deplist package1 [package2] […]
??????yum ?????????
????yum history [info|list|packages-list|packages-info|summary|addon-info|redo|undo|rollback|new|sync|stats]
????yum history
????yum history info 6
????yum history undo 6
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????yum repolist [all|enabled|disabled]
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????yum list
????yum list [all | glob_exp1] [glob_exp2] […]
????yum list {available|installed|updates} [glob_exp1][…]
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????yum clean [ packages | metadata | expire-cache |rpmdb | plugins | all ]
???????????棺
????yum makecache

????YUM????????
????yum???????????????????????rpm??????????????yum???????repodata????????????????????????????????????????????????????
????????????????????? ?????????????????yum??????centos??????????????汾(??centos6??7)??yum????????????centos???·??????(??6??7)?????????yum??????????????汾??yum????????????centos??????yum?????????????centos7??????????????yum??????????????????????????Packages(??????????????)??
??????????????rpm??????? rpm????????????????????????????????????????????rpm???????????????????rpm????????Packages?????
????????????????????????? ???????????????????????????createrepo??????????yum???????????repodata????????????￡?
????createrepo  [/PATH/TO/REPODATA]  [/PATH/TO/RPM_PACKAGES/]
????createrepo centos/7 centos/7/Packages
??????????????yum?????????????ú???????????????????????о????????????????????????????????????yum??????????????ftp??http web????????????????????ú??yum?????????????????????????Ｔ?ɡ?
????YUM??????????
????yum???????????????/etc/yum.repos.d/???У???????????????????????yum????????????????????????????????yum??????????????????????.repo??β???????????????????????????????￡?
????[CentOS7]
????name=CentOS7 base repo
????baseurl=file:///misc/cd/
????gpgcheck=1
????gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS7
????enabled=1
????[CentOS7]  ?????yum????ID???????????????壬??????????????????????
????name=  ?????yum????????????????????
????baseurl=  ?????yum?repodata??????λ????б???file://??????ftp://??http://???????
????gpgcheck=  ?????????????????????????У?飬1?У?飬0???У??
????gpgkey=  ???gpgcheckУ?????λ??????gpgcheck?1????????????д?????????
????enabled=  ????????ò?????????1??????0???????
?????????У??????yum???λ?????/misc/cd???￡?????????rpm???????Packages???????????repodata????????????????baseurl=file:///misc/cd???·????
?????????ú??????????????yum clean all???????????yum???棬??????????????????yum???