sum --version (return code: 0)
sum (GNU coreutils) 8.25
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by Kayvan Aghaiepour and David MacKenzie.
sum --help (return code: 0)
Usage: sum [OPTION]... [FILE]...
Print checksum and block counts for each FILE.
With no FILE, or when FILE is -, read standard input.
-r use BSD sum algorithm, use 1K blocks
-s, --sysv use System V sum algorithm, use 512 bytes blocks
--help display this help and exit
--version output version information and exit
GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
Full documentation at: <http://www.gnu.org/software/coreutils/sum>
or available locally via: info '(coreutils) sum invocation'