sum (Unix)

sum

Original author(s)	Ken Thompson
Developer(s)	AT&T Bell Laboratories
Initial release	November 3, 1971 (1971-11-03)
Operating system	Unix, Unix-like, Inferno
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.

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.

The default algorithm on FreeBSD and GNU implementations is the SYSV checksum. Switching between the two algorithms is done via the command line -r.

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

External links

• sum(1) — manual pages from GNU coreutils