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sum(1)
NAME
sum - Displays the checksum and block count of a file
SYNOPSIS
sum [-o|-r] [file...]
The sum command reads file and calculates a 16-bit checksum and the number
of blocks in the file. If the file argument is omitted, sum reads standard
input.
STANDARDS
Interfaces documented on this reference page conform to industry standards
as follows:
sum: XPG4, XPG4-UNIX
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
OPTIONS
-o [Compaq] Uses an algorithm to compute the checksum using word-by-word
computation.
-r Uses an alternate algorithm to compute the checksum (rigorous byte-by-
byte computation rather than the word-by-word computation). This is
the default.
OPERANDS
file
The file for which a checksum is to be computed. If this operand is
omitted, standard input is used.
DESCRIPTION
The checksum and number of blocks are written to standard output. The sum
command is generally used to determine if a file that was copied or
communicated over transmission lines is an exact copy of the original. The
sum command writes the space used in 512-byte units.
System V Compatibility
[Compaq] The root of the directory tree that contains the commands
modified for SVID 2 compliance is specified in the file /etc/svid2_path.
You can use /etc/svid2_profile as the basis for, or to include in, your
.profile. The file /etc/svid2_profile reads /etc/svid2_path and sets the
first entries in the PATH environment variable so that the modified SVID 2
commands are found first.
[Compaq] The checksum algorithms for the default sum command and the SVID
2 compliant sum command are reversed. The SVID 2 compliant sum command
uses the word-by-word algorithm by default and uses the byte-by-byte
algorithm if you specify the -r option on the command line.
NOTES
1. [Compaq] The default algorithm is no longer the word-by-word
computation algorithm. It was changed to the 4.3BSD default
algorithm.
2. The algorithms used may not be portable, that is, the same checksum
may not be produced for the same input on different systems. Portable
applications should use cksum.
EXIT STATUS
The following exit values are returned:
0 Successful completion.
>0 An error occurred.
EXAMPLES
To display the checksum of datafile and the number of blocks in this file,
enter:
sum datafile
If the checksum of datafile is 1605 and if the file contains 3 blocks, sum
displays:
1605 3 datafile
ENVIRONMENT VARIABLES
The following environment variables affect the execution of sum:
LANG
Provides a default value for the internationalization variables that
are unset or null. If LANG is unset or null, the corresponding value
from the default locale is used. If any of the internationalization
variables contain an invalid setting, the utility behaves as if none of
the variables had been defined.
LC_ALL
If set to a non-empty string value, overrides the values of all the
other internationalization variables.
LC_CTYPE
Determines the locale for the interpretation of sequences of bytes of
text data as characters (for example, single-byte as opposed to
multibyte characters in arguments).
LC_MESSAGES
Determines the locale for the format and contents of diagnostic
messages written to standard error.
NLSPATH
Determines the location of message catalogues for the processing of
LC_MESSAGES.
SEE ALSO
Commands: cksum(1), wc(1)
Standards: standards(5)