apt-get upgarde和dist-upgrade的差别


apt-get upgarde和dist-upgrade的差别

apt-get upgarde和dist-upgrade的差别

  Debian/Ubuntu Linux都使用apt,升级时都是:    www.2cto.com   apt-get update  apt-get upgrade  apt-get dist-upgrade    但是常常有人会问,  upgrade和dist-upgrade有何不同,仔细查查,似乎大家对upgrade和dist-upgrade的解释
都有点不同,在此也纪录自己的看法.    我认为apt-get  upgrade和dist-upgrade的差别:   www.2cto.com     upgrade:系统将现有的Package升级,如果有相依性的问题,而此相依性需要安装其它新的
Package或影响到其它Package的相依性时,此Package就不会被升级,会保留下来.    dist-upgrade:可以聪明的解决相依性的问题,如果有相依性问题,需要安装/移除新的Package,
就会试着去安装/移除它.  (所以通常这个会被认为是有点风险的升级)    apt-get upgrade 和 apt-get dist-upgrade 本质上是没有什么不同的。   只不过,dist-upgrade  会识别出当依赖关系改变的情形并作出处理,而upgrade对此情形不处理。   例如软件包 a 原先依赖 b c d,但是在源里面可能已经升级了,现在是 a 依赖 b c  e。这种情况下,dist-upgrade 会删除 d 安装 e,并把 a 软件包升级,而 upgrade 会认为
依赖关系改变而拒绝升级 a  软件包。  www.2cto.com     man apt-get的解释:    upgrade: upgrade is  used to install the newest versions of all packages currently installed on the  system from the sources enumerated in /etc/apt/sources.list. Packages currently  installed with new versions available are retrieved and upgraded; under no  circumstances are currently installed packages removed, or packages not already  installed retrieved and installed. New versions of currently installed packages  that cannot be upgraded without changing the install status of another package  will be left at their current version. An update must be performed first so that  apt-get knows that new versions of packages are available.  dist-upgrade: dist-upgrade in addition to performing  the function of upgrade, also intelligently handles changing dependencies with  new versions of packages; apt-get has a "smart" conflict resolution system, and  it will attempt to upgrade the most important packages at the expense of  less   That which didn't kill me makes me stronger

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