[SOLVED] Remastering a Debian-live operating system

PaulExordium · 07-19-2022, 07:11 AM

On an installed Debian 11 system I'm trying to do a "simple" test of remastering an ISO file, without actual modifications, with the following script:

Code:

#!/bin/bash

mech="»»» "

isofile="debian-live-11.4.0-amd64-gnome.iso"
newisofile="new"$isofile

echo $mech$isofile
echo $mech$newisofile

echo $mech"Temporary directory to put the extracted files:"
tempdir=$(mktemp -d)
echo $mech$tempdir

echo $mech"Extract all files from the ISO:"
xorriso -osirrox on -indev $isofile -extract / $tempdir

echo $mech"Make the files in $tempdir writable:"
chmod -R +w $tempdir

###

echo $mech"Putting the ISO back together:"
xorriso -as mkisofs \
	-o $newisofile \
	-isohybrid-mbr /usr/lib/syslinux/isohdpfx.bin \
        -c isolinux/boot.cat \
        -b isolinux/isolinux.bin \
        -no-emul-boot \
        -boot-load-size 4 \
        -boot-info-table $tempdir

echo $mech"Remove "$tempdir" :"
rm -r $tempdir

exit
#        -isohybrid-mbr /usr/lib/syslinux/isohdpfx.bin \    
#        -isohybrid-mbr /usr/lib/ISOLINUX/isohdpfx.bin \
#xorriso : FAILURE : Given path does not exist on disk: -boot_image system_area='/usr/lib/syslinux/isohdpfx.bin'
#xorriso : FAILURE : Given path does not exist on disk: -boot_image system_area='/usr/lib/ISOLINUX/isohdpfx.bin'

And I get the "Given path does not exist on disk" error message.

Is this because it can't find the proper bootloader, and if so how can I correct my script?
If not what else should I be aware of?

PaulExordium · 07-20-2022, 09:23 AM

Running the command:

Code:

sudo apt-get install -y xorriso p7zip-full fakeroot binutils isolinux

Created this path:

Code:

/usr/lib/ISOLINUX/isohdpfx.bin

And that solved the problem. Apparently one or more package was missing.
Thanks for reading.

scdbackup · 07-20-2022, 11:47 AM

Hi,

congrats to your success and thanks for flying xorriso.

Just for the records:

You could have obtained the missing file content from the start of the
ISO image by

Code:

dd if="$isofile" bs=1 count=446 of=mbr_template.bin

and used it instead of /usr/lib/syslinux/isohdpfx.bin

Code:

...
-isohybrid-mbr mbr_template.bin \
...

(The MBR code should match the El Torito boot image isolinux.bin that's in
the ISO. So it is best to use the MBR code of the ISO rather than the
currently installed isohdpfx.bin. But since ISOLINUX gets more or less no
development any more, you'd need very old ISOs to see an actual mismatch.)

Have a nice day

Thomas

teckk · 07-20-2022, 04:32 PM

My 2 cents. Quote your variables. Quote your variables in the echo statement, then quote the whole statement.

Code:

newisofile="new"$isofile""

echo ""$mech""$isofile""
echo ""$mech""$newisofile""

echo ""$mech"Temporary directory to put the extracted files:"

echo ""$mech""$tempdir""

echo ""$mech"Extract all files from the ISO:"

xorriso -osirrox on -indev "$isofile" -extract / "$tempdir"

Why is that important?
https://linuxconfig.org/correct-vari...uoting-in-bash
https://stackoverflow.com/questions/...shell-variable

PaulExordium · 07-21-2022, 09:29 AM

scdbackup,
I did as you suggested, put the new ISO on a multiboot USB stick (all Linux-based OS) with the "MultiBootUSB-9.2.0" tool and ran it: flawless!
Thank you.

PaulExordium · 07-21-2022, 09:30 AM

teckk,
thank you for your links. They add to my modest knowledge of bash sripting.