What is the difference between yum update
and yum upgrade
, and when should I use one over the other?
CentOS Yum – Difference Between yum update and yum upgrade
centosupgradeyum
Related Solutions
This seems to be the same question as How do I keep Centos at version 6.3? and the second answer that might help you achieve what you want: https://serverfault.com/a/500606
Something like this might work:
yum --releasever=7.0 update
You may have to adapt as I'm not sure what releasever
your currently installed CentOS uses, maybe you also need to use 7.1.
The latter answers to Yum: How can I view variables like $releasever, $basearch & $YUM0? should help you with that.
Although another source mentions that this might still draw updates from later point releases, see http://www.linuxquestions.org/questions/linux-server-73/rhel-yum-update-without-migrating-to-point-releases-4175456496/
FWIW, this was also already asked the same way as How can I keep the RHEL version static (e.g. RHEL 5.1)? but I don't think that solution will work as cleanly as the above or if it will work at all.
Ubuntu / Debian etc. using apt-get:
You should first run
update
, thenupgrade
. Neither of them automatically runs the other.
apt-get update
updates the list of available packages and their versions, but it does not install or upgrade any packages.apt-get upgrade
actually installs newer versions of the packages you have. After updating the lists, the package manager knows about available updates for the software you have installed. This is why you first want toupdate
.
- Source.
However with Red Hat / CentOS using yum the update
command will ask you if you want to apply the updates it finds.
$ sudo yum update
grabs a list of all available updates and asks you if you would like to apply them. Like this:
[..]
kf5-sonnet-core x86_64 5.33.0-1.el7 epel 150 k
kf5-sonnet-ui x86_64 5.33.0-1.el7 epel 141 k
Transaction Summary
==================================================================================================================================================
Upgrade 52 Packages
Total size: 15 M
Is this ok [y/d/N]:
When your friend refers to update as "small changes" and upgrade as "big changes" he actually means the difference between upgrade and dist-upgrade.
From the apt-get manual:
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 important ones if necessary. The dist-upgrade
command may therefore remove some packages. The
/etc/apt/sources.list file contains a list of locations from which
to retrieve desired package files. See also apt_preferences(5) for
a mechanism for overriding the general settings for individual
packages.
Best Answer
yum upgrade
forces the removal of obsolete packages, whileyum update
may or may not also do this. The removal of obsolete packages can be risky, as it may remove packages that you use.This makes
yum update
the safer option.From
man yum
: