checking a burned CD against an ISO

[Chris F.A. Johnson]

On Tue, 22 May 2007, Sy Ali wrote:

> Because of some odd issue with k3b not verifying a burned disk, I went
> ahead and explored a better way to compare the disk.  Thanks to some
> earlier advice I already had the groundwork, but I wanted to make
> things a bit easier.
>
> So I came up with the following script.
>
> It seems to work fine - and both works and fails under the correct
> circumstances.. but is there anything which anyone here would change
> to make for less cutting-and-pasting or cleaner/happier code?
>
>
> ISO_FILENAME=pclinuxos-2007.iso
> MD5_FILENAME=pclinuxos-2007.md5sum
> DEVICE=/dev/dvd


     I'd use command-line parameters:

ISO_FILENAME=$1
MD5_FILENAME=$2

> DEVICE=/dev/dvd
>
> # SOURCE_MD5=`md5sum $ISO_FILENAME`
> SOURCE_MD5=`cat $MD5_FILENAME`

     No need for an external command:

read SOURCE_MD5 < $MD5_FILENAME

> # Remove the trailing filename
> SOURCE_MD5=`echo $SOURCE_MD5 | sed "s/$ISO_FILENAME$//"`

     No need for an external command:

SOURCE_MD5=${SOURCE_MD5%% *}

     Or combine both commands:

read SOURCE_MD5 junk < "$MD5_FILENAME"

> FILESIZE=$(stat -c%s "$ISO_FILENAME")
> DISK_MD5=`dd if=$DEVICE | head -c $FILESIZE | md5sum`

     No need for more than one external command:

DISK_MD5=$( md5sum "$DEVICE" )

> # Remove the trailing hyphon
> DISK_MD5=`echo $DISK_MD5 | sed "s/-$//"`

     No need for an external command:

DISK_MD5=${DISK_MD5%-}

> echo ""
> echo ""
> echo ""

     Only one command is needed:

printf "\n\n\n"

> if [ $SOURCE_MD5 = $DISK_MD5 ]; then
>  echo "$ISO_FILENAME: OK"
> else
>   echo "Sorry, your disk is not ok"
>   echo "I checked $ISO_FILENAME against $MD5_FILENAME"
>   echo ""
>   echo "md5sum was $SOURCE_MD5"
>   echo "cd sum was $DISK_MD5"
> fi

-- 
    Chris F.A. Johnson                      <http://cfaj.freeshell.org>
    ========= Do not reply to the From: address; use Reply-To: ========
    Author:
    Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
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