“yum update” updates all the presently installed packages to their latest versions that are available in the repositories and “yum upgrade” performs the same action as “yum update”, but once finished it also removes all of the obsolete packages from the system.

What is yum update command in Linux?

YUM (Yellowdog Updater Modified) is an open source command-line as well as graphical based package management tool for RPM (RedHat Package Manager) based Linux systems. It allows users and system administrator to easily install, update, remove or search software packages on a systems.

Is it safe to run yum update?

Yes, update. RHEL (and therefore CentOS) are careful not to update versions to anything incompatible, instead they backport bugfixes and security fixes, so the actual changes to packages are minimal and reasonably unlikely to cause compatibility problems.