The xrootd tools used by FGST are in the release directory of the glastdat user. Sourcing the wk_env script will set the PATH to a release bin directory and set the PYTHONPATH for the python packages.
cd /u/gl/glastdat/releases/admin/ . bin/wk_env
admin% ScaRunOnHosts -f glastsol -p -w -e -r -- SrvMpsPurge.sh -l