svcadm(1M)을 검색하려면 섹션에서 1M 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
cksum(1)
cksum(1) User Commands cksum(1)
NAME
cksum - write file checksums and sizes
SYNOPSIS
/usr/bin/cksum [file...]
DESCRIPTION
The cksum command calculates and writes to standard output a cyclic
redundancy check (CRC) for each input file, and also writes to standard
output the number of octets in each file.
For each file processed successfully the cksum method writes in the
following format:
"%u %d %s\n" <checksum>, <# of octets>, <path name>
If no file operand was specified, the path name and its leading space
is omitted.
The CRC used is based on the polynomial used for CRC error checking in
the referenced Ethernet standard.
The encoding for the CRC checksum is defined by the generating polyno‐
mial:
G(x) = x**32 + x**26 + x**23 + x**22+ x**16 + x**12 + x**11
+ x**10 + x**8 + x**7 + x**5 + x**4 + x**2 + x + 1
Mathematically, the CRC value corresponding to a given file is defined
by the following procedure:
1. The n bits to be evaluated are considered to be the coeffi‐
cients of a mod 2 polynomial M(x) of degree n−1. These n
bits are the bits from the file, with the most significant
bit being the most significant bit of the first octet of the
file and the last bit being the least significant bit of the
last octet, padded with zero bits (if necessary) to achieve
an integral number of octets, followed by one or more octets
representing the length of the file as a binary value, least
significant octet first. The smallest number of octets capa‐
ble of representing this integer is used.
2. M(x) is multiplied by x ^32 (that is, shifted left 32 bits)
and divided by G(x) using mod 2 division, producing a
remainder R(x) of degree ≤ 31.
3. The coefficients of R(x) are considered to be a 32-bit
sequence.
4. The bit sequence is complemented and the result is the CRC.
OPERANDS
The following operand is supported:
file A path name of a file to be checked. If no file operands are
specified, the standard input is used.
USAGE
The cksum command is typically used to quickly compare a suspect file
against a trusted version of the same, such as to ensure that files
transmitted over noisy media arrive intact. However, this comparison
cannot be considered cryptographically secure. When compatibility with
existing cksum usage or values is not required, the digest(1) command
is recommended instead, as it provides more modern and secure algo‐
rithms.
Although input files to cksum can be any type, the results need not be
what would be expected on character special device files. Since this
document does not specify the block size used when doing input, check‐
sums of character special files need not process all of the data in
those files.
The algorithm is expressed in terms of a bitstream divided into octets.
If a file is transmitted between two systems and undergoes any data
transformation (such as moving 8-bit characters into 9-bit bytes or
changing Little Endian byte ordering to Big Endian), identical CRC val‐
ues cannot be expected. Implementations performing such transformations
can extend cksum to handle such situations.
ENVIRONMENT VARIABLES
See environ(7) for descriptions of the following environment variables
that affect the execution of cksum: LANG, LC_ALL, LC_CTYPE, LC_MES‐
SAGES, and NLSPATH.
EXIT STATUS
The following exit values are returned:
0 All files were processed successfully.
> 0 An error occurred.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE TYPEAT‐
TRIBUTE VALUE _ Availabilitysystem/core-os _ Interface StabilityCommit‐
ted _ StandardSee standards(7).
SEE ALSO
digest(1), sum(1), attributes(7), environ(7), standards(7), bart(8)
Oracle Solaris 11.4 28 Apr 2020 cksum(1)