2018-01-17 yum -y 什么意思 ：

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yum help 

显示如下； 

Options:

  -h, --help            show this help message and exit

  -t, --tolerant        be tolerant of errors

  -C, --cacheonly      run entirely from system cache, don't update cache

  -c [config file], --config=[config file]

                        config file location

  -R [minutes], --randomwait=[minutes]

                        maximum command wait time

  -d [debug level], --debuglevel=[debug level]

                        debugging output level

  --showduplicates      show duplicates, in repos, in list/search commands

  -e [error level], --errorlevel=[error level]

                        error output level

  --rpmverbosity=[debug level name]

                        debugging output level for rpm

  -q, --quiet          quiet operation

  -v, --verbose        verbose operation

-y, --assumeyes answer yes for all questions

  --assumeno            answer no for all questions

  --version            show Yum version and exit

  --installroot=[path]  set install root

  --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

  --disableincludes=[repo]

                        disable includepkgs 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

  --releasever=RELEASEVER

                        set value of $releasever in yum config and repo files

  --downloadonly        don't update, just download

  --downloaddir=DLDIR  specifies an alternate directory to store packages

  --setopt=SETOPTS      set arbitrary config and repo options

  --bugfix              Include bugfix relevant packages, in updates

  --security            Include security relevant packages, in updates