From OLPCYellow Dog Updater, Modified, better known as “yum”, is a tool used by some Linux distributions to keep operating systems up-to-date. yum does for the operating system what the software update control panel does for Sugar and activities.
The differences between the software updater and yum are significant. The software updater looks like a Sugar activity, only updates Sugar activities, and can be run by anybody; yum is a text-only program, affects the operating system, and must be run by the super-user (or “root”). Although it is highly unlikely, it is possible to remove files that are essential for your XO to function.
As with the software updater, you must be connected to a network in order to use yum.
Please see the yum article for brief introduction on how to use yum.