Hi, Richard Owlett wrote: > > > xorriso -osirrox on ... -extract / /media/richard/netinst1
i wrote: > > (This is just one way to copy the directory tree out of the ISO into > > a disk tree. xorriso packs them up and packs them out.) > I assumed that using xorriso on both ends would give me a "byte for byte" > copy. No, that's the job of "dd" or similar copy programs. > > > 1. Grub2 will recognize it as a legit OS. You will have to teach it by configuration file entries like described in https://wiki.gentoo.org/wiki/GRUB2/Chainloading https://superuser.com/questions/154133/grub-boot-from-iso I wrote some remarks about that to Ethan Andrews in "Re: How do I boot a Debian 9.1.0 amd64 iso from GRUB?" https://lists.debian.org/debian-user/2017/09/msg00516.html Your mileage may vary when the booted kernel expands its realm from the initial RAM-disk to the ISO filesystem in the partition. It depends much on the software in the initial RAM-disk and in the ISO whether this will work. Pascal Hambourg mentions problems with the initial RAM-disk content in https://lists.debian.org/debian-user/2017/09/msg00566.html Felix Miata pointed to the naked kernels and initial RAM-disk images https://lists.debian.org/debian-user/2017/09/msg00568.html I guess he means things like http://ftp.nl.debian.org/debian/dists/testing/main/installer-amd64/current/images/hd-media/ sparsely described in http://ftp.nl.debian.org/debian/dists/testing/main/installer-amd64/current/images/MANIFEST > > > 2. if the partition is on a USB flash drive it will boot normally > > > on suitable hardware. If you do not want to modify the installed GRUB on the hard disk on that system, then you will need a GRUB on that USB stick which gets preferred by the firmware over the GRUB on hard disk, and then does the booting of the operating system in the ISO. > > > 3. all directories and files shall be modifiable. > > But actually you want a runnable normal GNU/Linux. > I want a "thingy/dodad/whatsit" that will install Debian to another > location, be it device or partition. If you do not want to unpack the ISO then you cannot directly modify files. (I assume ISO 9660 multi-session is not what you intend, but rather normal filesystem operations from the running operating system.) So you would need a separate writable filesystem and overlay it over the ISO when the operating system is running. But a Debian installation ISO is not prepared for doing that out of the box, afaik. So you would have to make your own ISO which has such capabilities. The hard part is modifying an unpacked Debian installation ISO so that it can do what you want when it gets started from an ISO in a partition. Maybe the pieces mentioned by Felix Miata can help. Packing up such ISO would not be difficult. One would not have to make it bootable by firmware by MBR or EFI system partition, because your USB stick's GRUB would be set up to be started by the firmwares. Question at that point is of course why one would want to have a read-only filesystem like ISO 9660 in the partition. The only reason would be if one wants to easily reset the filesystem by erasing the overlay filesystem, or if one could not get the Debian software inside the ISO to work from some suitable read-write filesystem. Have a nice day :) Thomas