| Original author(s) | Ken Thompson |
|---|---|
| Developer(s) | AT&T Bell Laboratories |
| Initial release | November 3, 1971 |
| Operating system | Unix, Unix-like, Inferno |
| Platform | Cross-platform |
| Type | Command |
| License | coreutils: GPLv3+ |
sum is a legacy utility available on some Unix and Unix-like operating systems. This utility outputs the checksum of each argument file, as well as the number of blocks they take on disk.[1]
Overview
The sum program is generally only useful for historical interest. It is not part of POSIX. Two algorithms are typically available: a 16-bit BSD checksum and a 32-bit SYSV checksum. Both are weaker than the (already weak) CRC32 used by cksum.[2]
The default algorithm on FreeBSD and GNU implementations is the weaker BSD checksum. Switching between the two algorithms is done via command line options.[2][1]
Syntax
The sum utility is invoked from the command line according to the following syntax:
sum [OPTION]... [FILE]...
with the possible option parameters being:
-r- use BSD checksum algorithm, use 1K blocks (defeats -s)
-s,--sysv- use SYSV checksum algorithm, use 512 bytes blocks
--help- display the help screen and exit
--version- output version information and exit
When no file parameter is given, or when FILE is -, the standard input is used as input file.
See also
- GNU Core Utilities
- UnxUtils port to native Win32
References
External links
- — manual pages from GNU coreutils