sum (Unix)

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]

sum

Original author(s)	Ken Thompson
Developer(s)	AT&T Bell Laboratories
Initial release	November 3, 1971
Operating system	Unix, Unix-like, Inferno
Type	Command
License	coreutils: GPLv3+

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

1. sum(1) — manual pages from GNU coreutils
2. sum(1) – FreeBSD General Commands Manual

External links

• sum(1) — manual pages from GNU coreutils