m.dem.extract

The commands m.dem.examine and m.dem.extract talk about blocksize. What
is blocksize? I tried to use m.dem.extract
I typed m.dem.extract input=(filename) output=(newfilename) then after the
program worked for a while it crashed and filled up my hard drive. Under
$LOCATION/.tmp there was two files created that were extremely large. I
deleted these files and the size of my hard drive was normal. any help
would be appreciated.
                        Bob Atnip
                        Camp Atterbury
                        (812) 526-1249
                        atnip@osiris.cso.uiuc.edu