说说 update 和 upgrade 的区别

对于一个运维站长来说更新和升级是个绕不开的工作，update和upgrade这两个单词一定是都不陌生的，虽然都是升级或者更新的意思，很多站长很难搞懂两个单词到底有什么区别（其实在软件更新方面两个是可以通用的）。最基本的讲，update是“更新”的意思，而upgrade则是“升级”的意思。

upgrade V.S. update：英文解释

update：

• to make sth more modern by adding new parts
• to give sb the most recent information about sth

upgrade:

• to make a piece of machinery, computer system, etc. more powerful
• to give sb a more important job
• to give sb a better seat on a plane, room in a hotel, etc. than the one that they have paid for

update和upgrade的主要区别

update是更新的意思，主要是为原有的东西增加新功能，或者对已有的部分做出更改等。比如，有人告诉你他换了新手机号码，你在你的手机上删掉了原有的号码并换成新的号码，那么就是update，而不能用upgrade

upgrade是升级的意思，是指从较低级版本升级到高级的版本，这种升级往往伴有新功能的增加，因此也有update的意思。但是，如果是给予某人升职、坐飞机时的升舱等，只能用upgrade，而不能用update。

因此在计算机领域，软件、系统的更新和升级往往是同一个意思，在这种环境中update和upgrade是可以通用的。只是往细了说update是量上的变化，而upgrade质上的变化。

yum update和upgrade的区别？

首先yum update和yum upgrade的功能是一样的，都是将需要更新的package更新至软件源中的最新版。

唯一不同是：yum upgrade会删除旧版本的package，而yum update则会保留。

注意！如果你的某些软件依赖旧版本的package，请使用yum update。

附赠关于yum update和upgrade的区别英文最全解释：

yum update originally just did upgrades of packages to new versions.
If, for example, foo-awesome obsoleted foo, yum update wouldn't offer
to upgrade from foo to foo-awesome. Adding the --obsoletes flag to yum
update made it do the extra checks to also offer that upgrade path.
yum upgrade was added as (essentially) an alias for yum --obsoletes
update. Since this is the behavior that almost everyone wants all of
the time, the configuration option obsoletes=1 was added to the
default /etc/yum.conf, making yum update and yum upgrade equivalent on
any recent, stock, Fedora/RHEL/CentOS/etc.

If you want to avoid kernel updates when you're running yum update,
you can just do yum --exclude=kernel* update. If you want automatic
updates on, but you want to avoid automatic kernel upgrades, then
adding the exclude to yum.conf is probably the right answer.

There probably isn't a Right Answer for your question. RHEL and
RHEL-based distributions don't have the same philosophy as the Debian
developers when it comes to updates, so the tools don't encourage the
same sorts of behavior.