check_syntax: detect if grep is BSD version, abort if no GNU-version found
check_syntax: detect if grep is BSD version, abort if no GNU-version found

MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3