Arch Linux

paozaf

Member

Registered: 2012-11-29

Posts: 68

[SOLVED] md5sum from a cd

Hi at all,
I would like to check if an installation CD of Arch is ok or not.
I think that I can use md5sum but unfortunately I don't have the iso file, just the CD.
Is there a way to check if the data into the disk are corrupted or not?
The OS installation was perfect...I had no problem.
Thanks a lot.

Last edited by paozaf (2012-11-29 15:27:36)

diiis

Member

Registered: 2012-06-06

Posts: 33

Re: [SOLVED] md5sum from a cd

sudo dd if=/dev/X | md5sum

should work, where X is the device name of your CD drive.

paozaf

Member

Registered: 2012-11-29

Posts: 68

Re: [SOLVED] md5sum from a cd

Perfect, it seems to work.
Just a question, your command returns to me this:
aefd90da1ee49c745101179f50afa783  -
The first part is ok, but I don't understand the second one...why there is spaces and then "-" instead of "archlinux-2012.10.06-dual.iso"?
Is it normal? Is the cd ok?
Thanks again

alphaniner

Member

From: Ancapistan

Registered: 2010-07-12

Posts: 2,810

Re: [SOLVED] md5sum from a cd

The "-" indicates the sum was calculated from stdin.  It's there in place of a filename, and will always happen when data is piped to md5sum:

$ echo foobar | md5sum
14758f1afd44c09b7992073ccf00b43d  -

---

But whether the Constitution really be one thing, or another, this much is certain - that it has either authorized such a government as we have had, or has been powerless to prevent it. In either case, it is unfit to exist.
-Lysander Spooner

paozaf

Member

Registered: 2012-11-29

Posts: 68

Re: [SOLVED] md5sum from a cd

Ah, ok...so the disk is ok, right?

alphaniner

Member

From: Ancapistan

Registered: 2010-07-12

Posts: 2,810

Re: [SOLVED] md5sum from a cd

All you really know at this point is that the disk is readable.  To check it's identical to the iso, you'd need to find the md5sum of the iso, which according to this is

aefd90da1ee49c745101179f50afa783

Since that matches the sum you calculated, now you know the disc is ok.

If you wanted to test the disc on the fly, you could create a file (say the file is called disc.md5) containing

aefd90da1ee49c745101179f50afa783  -

and run

sudo cat /dev/X | md5sum -c disc.md5

If the disc is good, the output would be

-: OK

Again, the "-" indicates the data tested came from stdin.

Last edited by alphaniner (2012-11-29 15:23:41)

---

But whether the Constitution really be one thing, or another, this much is certain - that it has either authorized such a government as we have had, or has been powerless to prevent it. In either case, it is unfit to exist.
-Lysander Spooner

paozaf

Member

Registered: 2012-11-29

Posts: 68

Re: [SOLVED] md5sum from a cd

Ok, all is ok
Thanks for your support.