.\" @(#)sum.1 6.1 (Berkeley) %G%
sum \- sum and count blocks in a file
calculates and prints a 16-bit checksum for the named file,
and also prints the number of blocks in the file.
It is typically used to look for bad spots, or
to validate a file communicated over
is indistinguishable from end of file on
most devices; check the block count.