Linux: Checking a CD and the ISO file

[Chris]

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Md5sum

You may notice this file on all download locations where Linux is available. It is a very useful file that you could download as this file holds a finger print of the ISO image. The finger print can be compared with the finger print of the ISO image that you have downloaded.

This finger print is way to determine that the file downloaded is bit for bit the same as the file on the server.

To check this, download Md5sum.exe from here.

As an example the ISO image shrike-i386-disc2 is going to be checked.

The file was downloaded from redhat where the md5sum file is also available.

Using Windows XP, open a Command Prompt: Start Menu, Programs, Accessories, Command Prompt.

OR...

Start, Run and Type: cmd

Make sure the ISO file and the md5sum.exe file are in the same location. From the Command Prompt change to the location of these files, for example type: cd desktop if the two files are on your desktop.

Now type: md5sum shrike-i386-disc1.iso

[include .iso]

Now press ENTER and wait a few seconds.

You should now see your finger print for this file.

Open the md5sum from the server; if you double click the file you will see text within your intenret explorer. You can also download and open the file with Notepad.

-----BEGIN PGP SIGNED MESSAGE-----

Hash: SHA1

34048ce4cd069b624f6e021ba63ecde5  shrike-i386-disc1.iso

6b8ba42f56b397d536826c78c9679c0a  shrike-i386-disc2.iso

af38ac4316ba20df2dec5f990913396d  shrike-i386-disc3.iso

0727c51ab359dafa9ab31e0c50958aa6  shrike-SRPMS-disc1.iso

2ddd8e6a8502869cd2e78d47590b9be1  shrike-SRPMS-disc2.iso

f378cf68b22c3b9a64c86b5067511630  shrike-SRPMS-disc3.iso

-----BEGIN PGP SIGNATURE-----

Version: GnuPG v1.0.7 (GNU/Linux)

iD8DBQE/YI35IZGAzdtCpg4RAvKnAKCdjWxxWvRUNOSYrXDVWFZzVG1oTgCcDdQi

Q2ngUUckqHAve4gh8ojUfPU=

=RmmX

-----END PGP SIGNATURE-----

Compare the two finger prints. If they match then you have the file you are after. If they are different, then file you have downloaded is different to the one on the server and because of this you will have to download the file again.

Linux Mediacheck

Certain Linux Distributions have what is known as Linux Mediacheck. It is a command that can be used to test a CD.

If the result of this check is PASS then you can use the CD. However if the result of this check is FAIL then you should not use the CD.

As an exapmle using the Fedore Core 1 you can make the check by typing:

Boot: linux mediacheck [see pic below]

To test the CD choose OK. [see pic below]

To being the testing choose Test and to check any other CD's choose Eject CD and replace the CD with the one to be tested. [see pic below]

The CD will now be be tested and can take about 5 minutes. [see pic below]

A PASS: [see pic below]

A FAIL: [see pic below]