UNIX for Dummies Questions & Answers

Hi all,

Ive been given a .bin file that I want to do a checksum on to make sure that it is consistant with what I know should be the checksum. I have tried using md5sum but it spits out a 128 bit line rather than a 32 bit line, which is what I want. Can someone help set me off in the right direction to develop a tool that will allow me to read each word in the .bin and compile a checksum together? I have never used unix before and I would like explanation on what I should do. Thanks in advance for any and all help.

Hi TeamUSA.

Look at cksum, or...

Perl has an excellent feature for this:

String::CRC::Cksum - Perl extension for calculating checksums in a manner compatible with the POSIX cksum program. - search.cpan.org

But I'm not quite sure why you want to "read each word and compile a checksum"

Hey scottn,

Thanks for sending me that. Im definitely going to take a look at it.

I dont think I explained my goals. Im still new to all this so I may have stated it wrong. Basically, I want to take a file name (with the path) as an input, and I would like the output to be a computed checksum. I believe the checksum should be a 32 bit sum of all the words I have in the bin file.

I'm going to see what that site gives me scottn but if anyone else has any solutions I'd be more than welcome to hear them. Thanks.

Well a simple way to include the file and the contents in the checksum would be:

Code:

(echo file1; cat file1) | cksum

Best you read up, all the same!

Thanks scottn. I dont exactly know where to put all of this in. Do i type this into terminal and then just hit return? I dont understand how programming in terminal works. haha thanks again.

You could run it from the command line as you say, or from a script.

You can program "in the terminal" exactly as you would in a script.

If your shell is /bin/ksh, for example (echo $0 to see what shell you are running), you can type ksh commands on the command line exactly as you would write them in a script.

So whether you run

Code:

(echo $PWD/file1; cat file1) | cksum

from the command line, or put it into a file and execute the file, the result is the same.

If you're very new to this you might want to avoid Perl just for now!

haha thanks again scottn. I really want to get Perl so im hoping to stick it out. So basically, i can type (echo $PWD/file1; cat file1) | cksum in the terminal and type in the file path where you have file1? Sorry for being so new to this.