sum [-r] [file...]
The sum utility calculates and prints a 16-bit checksum for the named file and the number of 512-byte blocks in the file. It is typically used to look for bad spots, or to validate a file communicated over some transmission line.
The following options are supported:
-r Use an alternate (machine-dependent) algorithm in computing the checksum.
The following operands are supported:
file A path name of a file. If no files are named, the standard input is used.
See largefile(5) for the description of the behavior
of sum when encountering files greater than or equal to 2 Gbyte ( 2
See environ(5) for descriptions of the following environment variables that affect the execution of sum: LC_CTYPE, LC_MESSAGES, and NLSPATH.
The following exit values are returned.
0 Successful completion.
>0 An error occurred.
See attributes(5) for descriptions of the following attributes:
cksum(1), sum(1B), wc(1), attributes(5), environ(5), largefile(5)
"Read error" is indistinguishable from end of file on most devices; check the block count.
Portable applications should use cksum(1).
sum and usr/ucb/sum (see sum(1B)) return different checksums.