Check_files to show size in GB


I am trying to get check_files to show me the size of a file in GB

path=FILENAME" show-all "detail-syntax=%(filename): %(size)"

and I get -

OK: 0/1 files (FILENAME: 24029822976)

How do I change the units to GB?

How do I add perf data on the size in GB?

How do I remove the ‘ok :0/1 files’ bit and just have %(filename): %(size) ?