I am trying to run a software from github using root under ubuntu linux 20.10 i have tried everything from installing CLion as well i am not sure if it helps or not any advice and opinions are welcomed
I guess you are trying to build some software using cmake, right?
You need to tell the system where to find ROOT, the easiest way to do this is to source $ROOTSYS/bin/thisroot.sh. where $ROOTSYS is the location of your ROOT install. This should load the environment variables necessary for your compilation to work. I believe the default path for the installation is in /opt but I could be wrong.
I think the first problem to solve is the fatal error related to a git command that the build procedure tries to run. I don’t know where that comes from, but I doubt the rest of the build can go on smoothly if a repository failed to be cloned.
Maybe running cmake with some --trace.. options might clarify where the problem comes from. Or maybe the developers of the software you are trying to install might be able to help.
For the ROOT part: as @lobis said you need to have a working ROOT installation in your environment to get rid of that error.