Yum (Yellow dog Updater Modified) is an RPM manager that provides facilities for downloading, installing and upgrading programs.
In a terminal
# yum check-update
will tell you what updates are available and applicable to your system. You could create a simple cron job of your own to email that to you, or you could modify /etc/cron.daily/yum.cron to do it (that is what the yum rc.d script enables), or you could install yum-applet (see http://www.fedoranews.org/tchung/yum-applet/ ) for a gui desktop indicator.
Other commonly used Yum commands are update, install and clean. To update all existing packages on your system enter:
$ yum update
To install a package foo:
$ yum install foo
To remove a package foo:
$ yum remove foo
Note that foo can be a regular expression. To remove any old cached packages and headers from your system.
$ yum clean all
See the yum man page for more information.
You get an error message like:
Cannot find a valid baseurl for repo: updates
ToDo: Check your internet connection. If you need a proxy, set it with
export http_proxy=http://proxy:8080 export ftp_proxy=http://proxy:8080