Hello everybody,
I'm reading and learning a lot about TCP/IP protocols, and i want to know how to calculate the IP header checksum manually. I've searched for it EVERYWHERE! and none of options work.
I've read a function that does it pretty good, but i can't "translate" it into a human form so i can do it manually.
here's the code:
People, i've tried, i understand and know how to calculate using ones complement, hex conversion, binary conversion, AND, OR, XOR, NOT, and everything, but i can't do this .
Does anyone know the answer to this?
When I run "sum -r" on a file that I've down loaded from the sco website, the 1st set of numbers differs from the checksum on the download page but the
2nd set matches.
If I try to install the patch, I get errors.
Anyone has an answer? (3 Replies)
say i have these many file in a directory named exam.
1)/exam/newfolder/link.txt.
2)/exam/newfolder1/
and i create a tar say exam.tar
well the problem is,
when i read the tar file i dont find any metadata about the directories,as you cannot create a tar containig empty directories.
on the... (2 Replies)
Hello,
I'm trying to create a shell script (#!/bin/sh) which should tell me the age of a file in minutes...
I have a process, which delivers me all 15 minutes a new file and I want to have a monitoring script, which sends me an email, if the present file is older than 20 minutes.
To do... (10 Replies)
Friends,
I need help with the following in UNIX.
Merge all csv files in one folder considering only 1 header row and ignoring header of all other files.
FYI - All files are in same format and contains same headers.
Thank you (4 Replies)
Hello
I am communicating with two devices using my computer over UDP protocol. The application is running fine. When I monitored the UDP traffic using Wireshark software, I found that there were too many Checksum errors.
Please find attached the png file showing this error. I am about to... (0 Replies)
Hi,
I have an input like this
1 2 3 4
2 3 4 5
4 5 6 7
I would like to count the no. of columns and print a header with a prefix "Col".
I would also like to count the no. of rows and print as first column with each line number with a prefix "Row"
So, my output would be
... (2 Replies)
Hello There...
I have a sample input file ..
number:department:amount
125:Market:125.23
126:Hardware store:434.95
127:Video store:7.45
128:Book store:14.32
129:Gasolline:16.10
I will be doing some manipulations on all the records except the header, but the header should always be... (2 Replies)
I've been struggling with this one for quite a while and cannot seem to find a solution for this find/replace scenario. Perhaps I'm getting rusty.
I have a file that contains a number of metrics (exactly 3 fields per line) from a few appliances that are collected in parallel. To identify the... (3 Replies)
Discussion started by: verdepollo
3 Replies
LEARN ABOUT OSF1
sum
sum(1) General Commands Manual sum(1)NAME
sum - Displays the checksum and byte count in block-size (1024) units of a file
SYNOPSIS
sum [-o | -r] [file...]
The sum command reads file and calculates a 16-bit checksum and the byte count in block-size (1024) units in the file. If the file argu-
ment is omitted, sum reads standard input.
STANDARDS
Interfaces documented on this reference page conform to industry standards as follows:
sum: XCU5.0
Refer to the standards(5) reference page for more information about industry standards and associated tags.
OPTIONS
[Tru64 UNIX] Uses an algorithm to compute the checksum using word-by-word computation. Uses an alternate algorithm to compute the check-
sum (rigorous byte-by-byte computation rather than the word-by-word computation).
[Tru64 UNIX] This is the default.
OPERANDS
The file for which a checksum is to be computed. If this operand is omitted, standard input is used.
DESCRIPTION
The checksum and number of blocks are written to standard output. The sum command is generally used to determine if a file that was copied
or communicated over transmission lines is an exact copy of the original. The sum command writes the space used in 1024-byte units.
[Tru64 UNIX] The checksum is calculated using a rigorous byte-byte computation by default.
System V Compatibility
[Tru64 UNIX] The checksum algorithms for the default sum command and the SVID 2 compliant sum command are reversed. The SVID 2 compliant
sum command uses the word-by-word algorithm by default and uses the byte-by-byte algorithm if you specify the -r option on the command
line.
NOTES
The sum utility is marked LEGACY in XCU Issue 5. [Tru64 UNIX] The default algorithm is no longer the word-by-word computation algorithm.
It was changed to the 4.3BSD default algorithm. The algorithms used may not be portable, that is, the same checksum may not be produced
for the same input on different systems. Portable applications should use cksum.
EXIT STATUS
The following exit values are returned: Successful completion. An error occurred.
EXAMPLES
To display the checksum of datafile and the number of blocks in this file, enter: sum datafile
If the checksum of datafile is 1605 and if the file contains 3 blocks, sum displays: 1605 3 datafile
ENVIRONMENT VARIABLES
The following environment variables affect the execution of sum: Provides a default value for the internationalization variables that are
unset or null. If LANG is unset or null, the corresponding value from the default locale is used. If any of the internationalization vari-
ables contain an invalid setting, the utility behaves as if none of the variables had been defined. If set to a non-empty string value,
overrides the values of all the other internationalization variables. Determines the locale for the interpretation of sequences of bytes
of text data as characters (for example, single-byte as opposed to multibyte characters in arguments). Determines the locale for the for-
mat and contents of diagnostic messages written to standard error. Determines the location of message catalogues for the processing of
LC_MESSAGES.
SEE ALSO
Commands: cksum(1), wc(1)
Standards: standards(5)sum(1)