sum(1) — Commands
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.
FLAGS
-o[Digital] Uses an algorithm to compute the checksum using word-by-word computation.
-rUses an alternate algorithm to compute the checksum (rigorous byte-by-byte computation rather than the word-by-word computation). This is the default.
PARAMETERS
fileThe file for which a checksum is to be computed. If this parameter 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
[Digital] The root of the directory tree that contains the commands modified for SVID2 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 SVID2 commands are found first.
[Digital] The checksum algorithms for the default sum command and the SVID2 compliant sum command are reversed. The SVID2 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.
ENVIRONMENT VARIABLES
The following environment variables affect the execution of sum:
LANGProvides 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_ALLIf set to a non-empty string value, overrides the values of all the other internationalization variables.
LC_CTYPEDetermines 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_MESSAGESDetermines the locale for the format and contents of diagnostic messages written to standard error.
NLSPATHDetermines the location of message catalogues for the processing of LC_MESSAGES.
NOTES
1.[Digital] 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.
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
EXIT VALUES
The following exit values are returned:
0Successful completion
>0An error occurred