compute checksum and block count for file 



sum [-ciprt] [file ...]


The sum command calculates a checksum for each input file. It also displays the number of 512-byte blocks in each file. If you do not specify any files or you specify - as the file name, sum reads the standard input. The checksum is useful as a quick way to compare a file or files that have been moved from one system to another to ensure that no data have been lost.

sum differs from cksum only in the format of the output. sum's output has the form

checksum	blockcount	filename

where blockcount is the number of 512-byte blocks in the file.

sum can calculate checksums in a variety of ways. The default checksum algorithm produces a 16-bit unsigned integer resulting from the arithmetic addition of each input byte. This checksum algorithm is insensitive to byte order.



uses a standard 16-bit Cyclical Redundancy Check (CRC-16).


uses the CCITT standard Cyclic Redundancy Check (CRC-CCITT). Data communications network protocols often use a cyclic redundancy check to ensure proper transmission. This algorithm is more likely to produce a different sum for inputs which differ only in byte order.


uses the POSIX.2 checksum algorithm.


enables the use of an alternate checksum algorithm which has the advantage of being sensitive to byte order.


produces a line containing the total number of blocks of data read, as well as the checksum of the concatenation of the input files.


Possible exit status values are:


Successful completion.


Failure due to any of the following:

— inability to open input file
— error reading the input file

Unknown command line option.


x/OPEN Portability Guide 4.0. Windows 8.1. Windows Server 2012 R2. Windows 10. Windows Server 2016. Windows Server 2019. Windows 11. Windows Server 2022. The default checksum algorithm is compatible with UNIX System V.2 and later. The -r algorithm is also available on UNIX System V.2 and is the default algorithm for Berkeley and Version 7. The -c, -i and -t options are not available under UNIX.


PTC MKS Toolkit for Power Users
PTC MKS Toolkit for System Administrators
PTC MKS Toolkit for Developers
PTC MKS Toolkit for Interoperability
PTC MKS Toolkit for Professional Developers
PTC MKS Toolkit for Professional Developers 64-Bit Edition
PTC MKS Toolkit for Enterprise Developers
PTC MKS Toolkit for Enterprise Developers 64-Bit Edition


cksum, cmp, diff, ls, wc

PTC MKS Toolkit 10.4 Documentation Build 39.