Useful yum Variables
The following is a list of variables you can use for both yum commands and yum configuration files (i.e. /etc/yum.conf and .repo files).
$releasever
This is replaced with the package’s version, as listed in distroverpkg. This defaults to the version of the redhat-release package.
$arch
This is replaced with your system’s architecture, as listed by os.uname() in Python.
$basearch
This is replaced with your base architecture. For example, if $arch=i686 then $basearch=i386.
$YUM0-9
This is replaced with the value of the shell environment variable of the same name. If the shell environment variable does not exist, then the configuration file variable will not be replaced.
Reference: Redhat Docs.
