xorriso : FAILURE : Not a known command

Thomas Schmitt scdbackup at gmx.net
Thu Jun 1 17:37:36 CEST 2017


Hi,

i tested with the intermediate grub-mkrescue version of Debian 8.

  $ grub-mkrescue --version
  grub-mkrescue (GRUB) 2.02~beta2-22

Test case is to pack up the grub-mkrescue program as payload of a
bootable ISO. grub-mkrescue insists in some payload. One could as well
use some /tmp/dummy file instead of $(which grub-mkrescue).

One can see that it is neither the script nor the released binary,
because it fails without "--" before option -f :

  $ grub-mkrescue --output=/dev/null $(which grub-mkrescue) -f
  grub-mkrescue: invalid option -- 'f'
  Try 'grub-mkrescue --help' or 'grub-mkrescue --usage' for more information.
  $ echo $?
  64
  $

So the way to operate it is with "--":

  $ grub-mkrescue --output=/dev/null $(which grub-mkrescue) -- -f
  GNU xorriso 1.4.7 : RockRidge filesystem manipulator, libburnia project.
  ...
  Written to medium : 4421 sectors at LBA 0
  Writing to 'stdio:/dev/null' completed successfully.

  $ echo $?
  0
  $

But the --help text describes the behavior of script and released binary:

  $ grub-mkrescue --help
  ...
  Generates a bootable CD/USB/floppy image.  Arguments other than options to
  this program are passed to xorriso, and indicate source files, source
  directories, or any of the mkisofs options listed by the output of `xorriso
  -as mkisofs -help'.

  Option -- switches to native xorriso command mode.
  ...

The intermediate binary consumes the first "--" and thus does not let xorriso
switch to native command mode. The script and the released binary forward
all "--" arguments to xorriso, This causes the error message which Leslie
experiences, because -f is not a native xorriso command.


Given the pitfalls of program analysis, i deem above direct experiment
the most reliable way to determine the need for "--".


Have a nice day :)

Thomas




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