Mount bootable ISO or IMG file and change files

['chris']

hi

Howto mount bootable ISO or IMG file to change files and save these changes?

[Alzhy · Accepted solution]

I don't think you can do it directly. When you mount an ISO file - it will always be Read Only.

Your best bet is to find out how the ISO was created, its format and edit files from there. Then re-create the ISO.

What kind/type of ISO / IMG file are we talking about here?

[Lucifer Megacruel]

Hi chirs,

Of course that is possible. You need to mount the iso or img file as loop back , then make changes and exit.

eg

mount -o loop cdrom.iso /mnt/loop

cd /mnt/loop
make changes < Bla bla.>

umount /mnt/loop

Truly Evil
Lucifer Megacruel

[Lucifer Megacruel]

Sorry,

Just checked on what Alzhy said , it is mounted read only :P. You can copy contents and make use of mkisofs to recreate a new image.

Truly Evil
Lucifer Megacruel

[Lucifer Megacruel]

Hi,

Here's how I would do it :)

mkdir -p /mnt/loopback
mount -oloop cdrom.iso /mnt/loopback
mkdir -p /home/Lucifer/remaster
cp -rf /mnt/loopback/ /home/Lucifer/remaster

Now make we can make glorious modifications in /home/Lucifer/remaster . After we are doing we can create the iso image again.

mkisofs -R -b /mnt/loopback/isolinux/isolinux.bin -c /mnt/loopback/isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -o /home/Lucifer/new.iso /home/Lucifer/


The caveat is the CD's can be booted in floppy emulation mode , so the exact steps i said may not really apply. But it should work in most of the cases.


You can test the newly created images easily using qemu and see that it boots okay ( I am typing it from memory ). You can also use bochs too ( Bochs is somewhat slower , but it is very good for debugging the kernel)

qemu -net-none -m256 -boot cdrom -hdc /home/Lucifer/image.iso

Truly Evil
Lucifer Megacruel

['chris']

Thx a lot, I try to mount as a root user an img file on debian lenny and get this problem:

# mount -o loop binary.img /mnt/loopback
mount: you must specify the filesystem type

# file binary.img
binary.img: x86 boot sector; partition 1: ID=0x83, active, starthead 0, startsector 1, 593919 sectors

[Lucifer Megacruel]

Hi Chirs,

If it is a valid iso image, you should be able to mount it using
mount -tiso9660 -oloop cdrom.iso /mnt/loopback

If it is some hard disk image created using qemu or bochs, they you possibly may not be able to mount it.

to create an iso file from a cd, use the dd command

dd if=/dev/hdc /of=cdrom.iso ( put it in if what basically points to your cd drive )


Truly Evil
Lucifer Megacruel

['chris']

Thx again, this is not ISO-file, it's a bootable USB Live image file.

Anyway I can mount it using:

# mount -o loop,offset=512 binary.img_old /mnt/loopback

I don't know if I can do a change, that I really need, because I cannot see there
a linux file structure.

# cd /mnt/loopback
# ls
doc ldlinux.sys live md5sum.txt syslinux
# cd syslinux
# ls
boot.txt f1.txt f4.txt f7.txt footer.cfg menu.cfg syslinux.cfg
data f2.txt f5.txt f8.txt header.cfg prompt.cfg
f10.txt f3.txt f6.txt f9.txt help.cfg syslinux.bin

[Lucifer Megacruel]

Hi chris,

syslinux is basically a bootloader :). You wont find anything in that directory other than boot loader related stuff . Check the live directory. Basically the directory structure depends on configuration , there are some small linux distros that runs entirely of the initial ram disk.

Truly Evil
Lucifer Megacruel