Hello everybody, I have been using my social security number for my taxation purposes. But, I have been recently intimidated by my lawyer that since the crime of identity theft has been on the high I should be careful in using it. I am really concerned about this and need to know whether there are... (1 Reply)
Hi All,
I have the following input which i want to process using AWK.
Rows,NC,amount
1,1202,0.192387
2,1201,0.111111
3,1201,0.123456
i want the following output
count of rows = 3 ,sum of amount = 0.426954
Many thanks (2 Replies)
Hi
i data looks like this:
student 1
Subject1 45 55
Subject2 44 55
Subject3 33 44
//
student 2
Subject1 45 55
Subject2 44 55
Subject3 33 44
i would like to sum $2, $3 (marks) and divide each entry in $2 and $3 with their respective sums and print for each student as $4 and... (2 Replies)
I am trying to figure out the OS version of my Linux box. I got three commands:
# uname -a
Linux test01 2.6.18-238.el5 #1 SMP Thu Jan 13 15:51:15 EST 2011 x86_64 x86_64 x86_64
# cat /proc/version
Linux version 2.6.18-238.el5 (mockbuild@builder10.centos.org) (gcc version 4.1.2 20080704... (4 Replies)
I have a simple text file having payment amount value on each line. At the end of day 'n' number of payments created difference in amount that I need to match from this file.
I have information about how many payments created difference and difference amount. Please help me to build shell... (3 Replies)
I have a file that looks like this:
HP ColorPlotter Z-6100
ACMARTIN IP 192.168.x.x
"VIRTUAL HP ( C9468A ) PART 1 of 2 (REAL CARTRIDGE 1)"
"VIRTUAL HP ( C9468A ) PART 2 of 2 (REAL CARTRIDGE 1)"
181
181
"VIRTUAL HP ( C9471A ) PART 1 of 2 (REAL CARTRIDGE 2)"
"VIRTUAL HP ( C9471A ) PART 2... (4 Replies)
Discussion started by: SysAdminRialto
4 Replies
LEARN ABOUT OPENDARWIN
sum
CKSUM(1) BSD General Commands Manual CKSUM(1)NAME
cksum, sum -- display file checksums and block counts
SYNOPSIS
cksum [-o 1 | 2 | 3] [file ...]
sum [file ...]
DESCRIPTION
The cksum utility writes to the standard output three whitespace separated fields for each input file. These fields are a checksum CRC, the
total number of octets in the file and the file name. If no file name is specified, the standard input is used and no file name is written.
The sum utility is identical to the cksum utility, except that it defaults to using historic algorithm 1, as described below. It is provided
for compatibility only.
The options are as follows:
-o Use historic algorithms instead of the (superior) default one.
Algorithm 1 is the algorithm used by historic BSD systems as the sum(1) algorithm and by historic AT&T System V UNIX systems as the
sum(1) algorithm when using the -r option. This is a 16-bit checksum, with a right rotation before each addition; overflow is dis-
carded.
Algorithm 2 is the algorithm used by historic AT&T System V UNIX systems as the default sum(1) algorithm. This is a 32-bit checksum,
and is defined as follows:
s = sum of all bytes;
r = s % 2^16 + (s % 2^32) / 2^16;
cksum = (r % 2^16) + r / 2^16;
Algorithm 3 is what is commonly called the '32bit CRC' algorithm. This is a 32-bit checksum.
Both algorithm 1 and 2 write to the standard output the same fields as the default algorithm except that the size of the file in
bytes is replaced with the size of the file in blocks. For historic reasons, the block size is 1024 for algorithm 1 and 512 for
algorithm 2. Partial blocks are rounded up.
The default CRC used is based on the polynomial used for CRC error checking in the networking standard ISO/IEC 8802-3:1989. The CRC checksum
encoding is defined by the generating polynomial:
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:
The n bits to be evaluated are considered to be the coefficients 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
capable of representing this integer are used.
M(x) is multiplied by x^32 (i.e., shifted left 32 bits) and divided by G(x) using mod 2 division, producing a remainder R(x) of degree
<= 31.
The coefficients of R(x) are considered to be a 32-bit sequence.
The bit sequence is complemented and the result is the CRC.
DIAGNOSTICS
The cksum and sum utilities exit 0 on success, and >0 if an error occurs.
SEE ALSO md5(1)
The default calculation is identical to that given in pseudo-code in the following ACM article.
Dilip V. Sarwate, "Computation of Cyclic Redundancy Checks Via Table Lookup", Communications of the ACM, August 1988.
STANDARDS
The cksum utility is expected to conform to IEEE Std 1003.2-1992 (``POSIX.2'').
HISTORY
The cksum utility appeared in 4.4BSD.
BSD April 28, 1995 BSD