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MD5SUM of an ALREADY BURNED CD
( Also see: Check CD Script )



A few posts back I told you to do the md5sum on the ISO files themselves, just because that is far off the easy way !
However CD´s can be checked too, it only takes a little more.
First check if you have ¨isoinfo¨ installed on your Linux box.
Type in a console:

CODE
$ whereis isoinfo


If it´s not installed, look for it on your install-CD´s !

Here is how it is done ( my example here is a Slackware 9.0 CD )
Put the CD in your CD-rom player, and type in a console:

CODE
$ isoinfo -d -i /dev/cdrom


This will give you something like this:

QUOTE (Text @ Screen)
CD-ROM is in ISO 9660 format
System id: LINUX
Volume id: Slack9d1
Volume set id:
Publisher id: Slackware Linux, Inc. <info@slackware.com>
Data preparer id: Slackware Linux, Inc. <info@slackware.com>
Application id: Slackware Linux 9.0 disc 1
Copyright File id:
Abstract File id:
Bibliographic File id:
Volume set size is: 1
Volume set sequence number is: 1
Logical block size is: 2048
Volume size is: 339344
Joliet with UCS level 3 found
Rock Ridge signatures version 1 found


The only important info of this output are these two lines:

Logical block size is: 2048
Volume size is: 339344

Now, leave the CD in the player and type:

CODE
$ dd if=/dev/cdrom bs=2048 count=339344 conv=notrunc,noerror | md5sum


BEWARE: change the numbers with the ones you found in the previous output !!
This will produce a new output ( takes several minutes ! )

QUOTE (Text @ Screen)
339344+0 records in
339344+0 records out
563c1bfff307a16d45f5da04011f07b6 <===( This is the checksum number ! )


Now go to the mirror you have downloaded your ISO from ( or any other mirror ) and pick up the text-file md5sum. This textfile contains the original number:

QUOTE (Text @ Screen)
563c1bfff307a16d45f5da04011f07b6 slackware-9.0-install.iso


If this number matches the number you found in the output above, you can be sure your CD is integer !
In this case it was, but then I always check the numbers before burning my CD, ´cause that´s so much easier and does not turn any blank CD´s into coasters !


Bruno


-- May 14 2003 ( Revised Dec 9 2005 ) --


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