Change one file in an ISO image

Tim Judd tajudd at
Fri Sep 18 03:28:53 UTC 2009

On 9/17/09, John Nielsen <lists at> wrote:
> On Thursday 17 September 2009 17:09:28 Tim Judd wrote:
>> On 9/16/09, Gelsema, P (Patrick) - FreeBSD <freebsd at> wrote:
>> > I need to change one file in an existing ISO image. It is a DVD image
>> > btw. Unfortunately I dont have many options of changing the fie before
>> > creating the image.
>> the cd9660/iso9660 filesystem type doesn't support rw options.  Even
>> if you mdconfig and mount -o rw, it is mounted ro
> If your change does not require altering the size of the file you wish to
> edit
> you may be able to just use a hex editor. I don't know enough about the ISO
> 9660 filesystem to say whether and how often it fragments files, but for a
> localized change you should be able to find the block containing the
> original
> file data and alter it. On the plus side you can check your work by mounting
> the modified ISO image and making sure you got the right file, etc.
> JN

Until the CRC kicks in.

Copy, edit, remaster.  To me, there's a reason it's called 'mastering' a CDROM

I'm sorry, unionfs is the only other way, and unionfs isn't workable
on WinPE (to which the OP clearly stated that this is the disc he
wants to edit).

Bart's bbie (Bart's Boot Image Extractor), an win32 app will write the
image file in any iso or cdrom to a file.  re-use that file to specify
the el-torito boot image...  probably need no-emulation mode.

Until I see proof of "on the fly editing" of a CD-ROM image, I will
always preach that a CD-ROM cannot be altered except by remastering an

Thank you,

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