V8/usr/src/cmd/tbl/jcompr

echo $1
/usr/bin/tbl $1 | troff  >a$$junk
tbl $1 | troff  >b$$junk
if cmp a$$junk b$$junk; then echo "  OK";
else  echo DIFFERENT old a new b;ls -l *junk;  fi
rm a$$junk b$$junk