Lâmôlabs

Background

Have you ever needed to change the Volume ID on a pre-existing ISO file? I thought for sure there had to be a command-line tool that would allow for this. But after googling for over an hour I could only find 2 methods to do this.

1. The first was simply firing up a GUI, such as ISO Master and changing the Volume ID.
2. The second method involved remastering the ISO by copying the files out to a directory, and then essentially recreating a new .iso file.

Neither of these were exactly what I was looking for so I asked the question on serverfault.com. My question: Is there a way to change a .iso files volume id from the command line?. Thankfully someone answered and provided a pretty painless way to manipulate the Volume ID of a .iso file.

NOTE: The Volume ID I’m talking about is this string within a given .iso file, as seen in the example below, or more typically when you mount a CD/DVD in Windows Explorer or Nautilus as the CD/DVD’s label.

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% isoinfo -d -i /usr/share/virtualbox/VBoxGuestAdditions.iso | grep "Volume id"
Volume id: VBOXADDITIONS_4.1.8_75467

Solution

According to kupson, the person that answered my question, the Volume ID is stored at offset 0×8028 as a 32 byte ASCII string within the .iso file. With this information it’s pretty straightforward to put together a Perl script to manipulate the .iso file.

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#!/usr/bin/perl
 
# SCRIPT:         chkisovol.pl
# DESCRIPTION:    Change a given .iso file's Volume ID to something else
 
# references
#   - http://perldoc.perl.org/functions/open.html
#   - http://serverfault.com/questions/361474/is-there-a-way-to-change-a-iso-files-volume-id-from-the-command-line
 
use strict;
use warnings;
 
# usage
die "Use: $0 <iso_file> <new volume id>\n" unless @ARGV == 2;
 
#  open file for read/write updates (+<) doesn't clobber file 1st
open my $file, "+<", $ARGV[0] or die "Cannot open: $!";
seek $file, 0x8028,0;
 
# write new Volume ID all uppercased (uc). The -32.32s takes care of left
# aligning the output, and forcing it into a 32 byte long string
printf $file "%-32.32s", uc($ARGV[1]);

Now for a test.

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# Before
% isoinfo -d -i ~/netware.iso |grep "Volume id"
Volume id: VMWTOOLS
 
# Change the Volume ID
% ./chgisovol.pl ~/netware.iso SOMENEWVOL
 
# After
isoinfo -d -i ~/netware.iso |grep "Volume id"
Volume id: SOMENEWVOL

Again, thanks to kupson for providing the technique on how to accomplish this.

References

links

• Is there a way to change a .iso files volume id from the command line? – serverfault.com
• How can I change the volume label on DVD ISO’s? – ubuntuforums.org

NOTE: For further details regarding my one-liner blog posts, check out my one-liner style guide primer.