1.\" Copyright (c) 1991, 1993
2.\" The Regents of the University of California. All rights reserved.
3.\"
4.\" This code is derived from software contributed to Berkeley by
5.\" the Institute of Electrical and Electronics Engineers, Inc.
6.\"
7.\" Redistribution and use in source and binary forms, with or without
8.\" modification, are permitted provided that the following conditions
9.\" are met:
10.\" 1. Redistributions of source code must retain the above copyright
11.\" notice, this list of conditions and the following disclaimer.
12.\" 2. Redistributions in binary form must reproduce the above copyright
13.\" notice, this list of conditions and the following disclaimer in the
14.\" documentation and/or other materials provided with the distribution.
15.\" 3. All advertising materials mentioning features or use of this software
16.\" must display the following acknowledgement:
17.\" This product includes software developed by the University of
18.\" California, Berkeley and its contributors.
19.\" 4. Neither the name of the University nor the names of its contributors
20.\" may be used to endorse or promote products derived from this software
21.\" without specific prior written permission.
22.\"
23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33.\" SUCH DAMAGE.
34.\"
| 1.\" Copyright (c) 1991, 1993
2.\" The Regents of the University of California. All rights reserved.
3.\"
4.\" This code is derived from software contributed to Berkeley by
5.\" the Institute of Electrical and Electronics Engineers, Inc.
6.\"
7.\" Redistribution and use in source and binary forms, with or without
8.\" modification, are permitted provided that the following conditions
9.\" are met:
10.\" 1. Redistributions of source code must retain the above copyright
11.\" notice, this list of conditions and the following disclaimer.
12.\" 2. Redistributions in binary form must reproduce the above copyright
13.\" notice, this list of conditions and the following disclaimer in the
14.\" documentation and/or other materials provided with the distribution.
15.\" 3. All advertising materials mentioning features or use of this software
16.\" must display the following acknowledgement:
17.\" This product includes software developed by the University of
18.\" California, Berkeley and its contributors.
19.\" 4. Neither the name of the University nor the names of its contributors
20.\" may be used to endorse or promote products derived from this software
21.\" without specific prior written permission.
22.\"
23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33.\" SUCH DAMAGE.
34.\"
|
35.\" @(#)cksum.1 8.1 (Berkeley) 6/29/93
36.\" $Id: cksum.1,v 1.2 1997/04/27 08:45:43 jmg Exp $
| 35.\" @(#)cksum.1 8.2 (Berkeley) 4/28/95
36.\" $Id: cksum.1,v 1.3 1997/04/29 08:41:26 jmg Exp $
|
37.\"
| 37.\"
|
38.Dd June 29, 1993
| 38.Dd April 28, 1995
|
39.Dt CKSUM 1
40.Os BSD 4.4
41.Sh NAME
42.Nm cksum
43.Nd display file checksums and block counts
44.Sh SYNOPSIS
| 39.Dt CKSUM 1
40.Os BSD 4.4
41.Sh NAME
42.Nm cksum
43.Nd display file checksums and block counts
44.Sh SYNOPSIS
|
45.Nm
46.Op Fl o Op \&1 \&| \&2
| 45.Nm cksum
46.Op Fl o Ar \&1 No \&| Ar \&2
|
47.Op Ar file ...
48.Sh DESCRIPTION
49The
| 47.Op Ar file ...
48.Sh DESCRIPTION
49The
|
50.Nm
| 50.Nm cksum
|
51utility writes to the standard output three whitespace separated
52fields for each input file.
53These fields are a checksum
54.Tn CRC ,
55the total number of octets in the file and the file name.
56If no file name is specified, the standard input is used and no file name
57is written.
58.Pp
59The options are as follows:
60.Bl -tag -width indent
61.It Fl o
62Use historic algorithms instead of the (superior) default one.
63.Pp
64Algorithm 1 is the algorithm used by historic
65.Bx
66systems as the
67.Xr sum 1
68algorithm and by historic
69.At V
70systems as the
71.Xr sum
72algorithm when using the
73.Fl r
74option.
75This is a 16-bit checksum, with a right rotation before each addition;
76overflow is discarded.
77.Pp
78Algorithm 2 is the algorithm used by historic
79.At V
80systems as the
81default
82.Xr sum
83algorithm.
84This is a 32-bit checksum, and is defined as follows:
85.Bd -unfilled -offset indent
86s = sum of all bytes;
87r = s % 2^16 + (s % 2^32) / 2^16;
88cksum = (r % 2^16) + r / 2^16;
89.Ed
90.Pp
91Both algorithm 1 and 2 write to the standard output the same fields as
92the default algorithm except that the size of the file in bytes is
93replaced with the size of the file in blocks.
94For historic reasons, the block size is 1024 for algorithm 1 and 512
95for algorithm 2.
96Partial blocks are rounded up.
97.El
98.Pp
99The default
100.Tn CRC
101used is based on the polynomial used for
102.Tn CRC
103error checking
104in the networking standard
105.St -iso8802-3
106The
107.Tn CRC
108checksum encoding is defined by the generating polynomial:
109.Pp
110.Bd -unfilled -offset indent
111G(x) = x^32 + x^26 + x^23 + x^22 + x^16 + x^12 +
112 x^11 + x^10 + x^8 + x^7 + x^5 + x^4 + x^2 + x + 1
113.Ed
114.Pp
115Mathematically, the
116.Tn CRC
117value corresponding to a given file is defined by
118the following procedure:
119.Bd -filled -offset indent
120The
121.Ar n
122bits to be evaluated are considered to be the coefficients of a mod 2
123polynomial M(x) of degree
124.Ar n Ns \-1 .
125These
126.Ar n
127bits are the bits from the file, with the most significant bit being the most
128significant bit of the first octet of the file and the last bit being the least
129significant bit of the last octet, padded with zero bits (if necessary) to
130achieve an integral number of octets, followed by one or more octets
131representing the length of the file as a binary value, least significant octet
132first.
133The smallest number of octets capable of representing this integer are used.
134.Pp
135M(x) is multiplied by x^32 (i.e., shifted left 32 bits) and divided by
136G(x) using mod 2 division, producing a remainder R(x) of degree <= 31.
137.Pp
138The coefficients of R(x) are considered to be a 32-bit sequence.
139.Pp
140The bit sequence is complemented and the result is the CRC.
141.Ed
142.Pp
143The
144.Nm
145utility exits 0 on success, and >0 if an error occurs.
146.Sh SEE ALSO
147.Xr md5 1
148.Rs
149The default calculation is identical to that given in pseudo-code
150in the following
151.Tn ACM
152article.
153.Rs
154.%T "Computation of Cyclic Redundancy Checks Via Table Lookup"
155.%A Dilip V. Sarwate
156.%J "Communications of the \\*(tNACM\\*(sP"
157.%D "August 1988"
158.Re
159.Sh STANDARDS
160The
| 51utility writes to the standard output three whitespace separated
52fields for each input file.
53These fields are a checksum
54.Tn CRC ,
55the total number of octets in the file and the file name.
56If no file name is specified, the standard input is used and no file name
57is written.
58.Pp
59The options are as follows:
60.Bl -tag -width indent
61.It Fl o
62Use historic algorithms instead of the (superior) default one.
63.Pp
64Algorithm 1 is the algorithm used by historic
65.Bx
66systems as the
67.Xr sum 1
68algorithm and by historic
69.At V
70systems as the
71.Xr sum
72algorithm when using the
73.Fl r
74option.
75This is a 16-bit checksum, with a right rotation before each addition;
76overflow is discarded.
77.Pp
78Algorithm 2 is the algorithm used by historic
79.At V
80systems as the
81default
82.Xr sum
83algorithm.
84This is a 32-bit checksum, and is defined as follows:
85.Bd -unfilled -offset indent
86s = sum of all bytes;
87r = s % 2^16 + (s % 2^32) / 2^16;
88cksum = (r % 2^16) + r / 2^16;
89.Ed
90.Pp
91Both algorithm 1 and 2 write to the standard output the same fields as
92the default algorithm except that the size of the file in bytes is
93replaced with the size of the file in blocks.
94For historic reasons, the block size is 1024 for algorithm 1 and 512
95for algorithm 2.
96Partial blocks are rounded up.
97.El
98.Pp
99The default
100.Tn CRC
101used is based on the polynomial used for
102.Tn CRC
103error checking
104in the networking standard
105.St -iso8802-3
106The
107.Tn CRC
108checksum encoding is defined by the generating polynomial:
109.Pp
110.Bd -unfilled -offset indent
111G(x) = x^32 + x^26 + x^23 + x^22 + x^16 + x^12 +
112 x^11 + x^10 + x^8 + x^7 + x^5 + x^4 + x^2 + x + 1
113.Ed
114.Pp
115Mathematically, the
116.Tn CRC
117value corresponding to a given file is defined by
118the following procedure:
119.Bd -filled -offset indent
120The
121.Ar n
122bits to be evaluated are considered to be the coefficients of a mod 2
123polynomial M(x) of degree
124.Ar n Ns \-1 .
125These
126.Ar n
127bits are the bits from the file, with the most significant bit being the most
128significant bit of the first octet of the file and the last bit being the least
129significant bit of the last octet, padded with zero bits (if necessary) to
130achieve an integral number of octets, followed by one or more octets
131representing the length of the file as a binary value, least significant octet
132first.
133The smallest number of octets capable of representing this integer are used.
134.Pp
135M(x) is multiplied by x^32 (i.e., shifted left 32 bits) and divided by
136G(x) using mod 2 division, producing a remainder R(x) of degree <= 31.
137.Pp
138The coefficients of R(x) are considered to be a 32-bit sequence.
139.Pp
140The bit sequence is complemented and the result is the CRC.
141.Ed
142.Pp
143The
144.Nm
145utility exits 0 on success, and >0 if an error occurs.
146.Sh SEE ALSO
147.Xr md5 1
148.Rs
149The default calculation is identical to that given in pseudo-code
150in the following
151.Tn ACM
152article.
153.Rs
154.%T "Computation of Cyclic Redundancy Checks Via Table Lookup"
155.%A Dilip V. Sarwate
156.%J "Communications of the \\*(tNACM\\*(sP"
157.%D "August 1988"
158.Re
159.Sh STANDARDS
160The
|
161.Nm
162utility is expected to be POSIX 1003.2 compatible.
| 161.Nm cksum
162utility is expected to conform to
163.St -p1003.2-92 .
|
163.Sh HISTORY
164The
| 164.Sh HISTORY
165The
|
165.Nm
| 166.Nm cksum
|
166utility appeared in
167.Bx 4.4 .
| 167utility appeared in
168.Bx 4.4 .
|