MPE/iX Shell and Utilities Reference Manual, Vol 1

cksum(1) MPE/iX Shell and Utilities cksum(1)
NAME
cksum — compute checksum and byte count for file
SYNOPSIS
cksum [–ciprt][file ...]
DESCRIPTION
cksum calculates and displays a checksum for each input file. A checksum is an error-check-
ing technique used by many programs as a quick way to compare files that have been moved
from one location to another to ensure that no data has been lost. cksum also displays the
number of eight-bit bytes in each file. If you do not specify any files or you specify – as the
file name, cksum reads the standard input.
cksum differs from sum only in the format of the output. cksum’s output has the form
checksum bytecount filename
where bytecount is the number of bytes in the file.
cksum can calculate checksums in a variety of ways. The default is compatible with the
POSIX.2 standard. You can specify other algorithms by specifying options. The
POSIX stan-
dard does not recognize these algorithms; we provide them for compatibility with the sum
command.
Options
cksum accepts the following options:
–c uses a standard 16-bit Cyclical Redundancy Check (CRC-16).
–i uses the CCITT standard Cyclic Redundancy Check (CRC-CCITT). Data commu-
nications network protocols often use a cyclic redundancy check to ensure proper
transmission. This algorithm is more likely to produce a different sum for inputs —
the only difference is byte order.
–p uses the
POSIX.2 checksum algorithm. This is the default.
–r enables the use of an alternate checksum algorithm which has the advantage of being
sensitive to byte order.
–t produces a line containing the total number of bytes of data read as well as the
checksum of the concatenation of the input files.
Commands and Utilities 1-105