Re: Editing ISO files (Was: saving cheatcodes)

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

Cindy-Sue Causey wrote:
>  You can use isomaster to:
>  - add files to an image
>  - extract files from an image
>  - delete files from an image"

It would be interesting to see what happens if it adds a new session
to the existing image and has to update the Primary Volume Descriptor
to point to the new directory tree. At this stage, the MBR code and the
partition table are at risk. They are needed for booting from USB stick.
But
  https://sources.debian.org/src/isomaster/1.3.13-1/bk/bkWrite.c/
does not look much like multi-session.

If it creates a new ISO from the original and its changes, then it will
quite surely not enable the ISO for booting from USB stick nor will it
add an EFI System Partition. (At least i cannot spot any preparations in
the source code. Only El Torito for booting from DVD via BIOS is to see.)


I was tempted to propose to add a session by xorriso. But that might become
adventurous, because the layout of KNOPPIX 8.1 was not chosen with
multi-session in mind.
Given the fact that xorriso offers the opportunity to apply the final step
of the original production procedure, i deem this more suitable for
achieving the goal of a modified ISO.
(If that is the goal for which Denis decides, at all. The proposal by Gilles
is more focused on Denis' original wish.)


Jeffery Mewtamer wrote:
> I think I've come across isomaster before and deemed it unsuitable to
> my needs thanks to it being a graphical utility,

xorriso is entirely command driven. Either in batch mode or in a text
dialog mode similar to a shell session. Its "-as mkisofs" emulation is
less suitable for ISO 9660 editing, as it has no options for deletion
or renaming of files. So i would advise to use its native command mode,
where sequence of commands matters, like it does in a shell script.
See
  https://www.gnu.org/software/xorriso/
  https://www.gnu.org/software/xorriso/man_1_xorriso.html


But as said, bootable GNU/Linux ISOs are normally a delicate pile of
unusual add-on equipment. Any result of multi-session editing needs to
be inspected and tested very carefully.
(Please report any results or stumblestones if such an adventure gets
 started. Maybe it works out of the box, maybe it needs some tuning.)


Have a nice day :)

Thomas