背景
[root@poloyy ~]# yum makecache fast
usage: yum makecache [-c [config file]] [-q] [-v] [--version]
[--installroot [path]] [--nodocs] [--noplugins]
[--enableplugin [plugin]] [--disableplugin [plugin]]
[--releasever RELEASEVER] [--setopt SETOPTS]
[--skip-broken] [-h] [--allowerasing] [-b | --nobest]
[-C] [-R [minutes]] [-d [debug level]] [--debugsolver]
[--showduplicates] [-e ERRORLEVEL] [--obsoletes]
[--rpmverbosity [debug level name]] [-y] [--assumeno]
[--enablerepo [repo]] [--disablerepo [repo] | --repo
[repo]] [--enable | --disable] [-x [package]]
[--disableexcludes [repo]] [--repofrompath [repo,path]]