Using Environment Variables in %files section of SPEC File



I have just started using RPM Packager. While creating the SPEC file I
am facing some Issues. The required file for packaging are in $STAGING
directory, where STAGING is an environment variable set in Linux.
I am specifying it in %files tag as


%files


$STAGING/linux/readme.html


I am getting an error for this. Can someone please guide me on how to
use the Linux Environment variable in %files section.

.