sum — checksum and count the blocks in a file
sum [OPTION...] [FILE...]
Print checksum and block counts for each FILE.
−rdefeat −s, use BSD
sum algorithm, use 1K blocks
−s, −−sysvuse System V sum algorithm, use 512 bytes blocks
−−helpdisplay this help and exit
−−versionoutput version information and exit
With no FILE, or when FILE is −, read standard input.