For example:
- virt-cat --format=raw -a disk.img
+ virt-cat --format=raw -a disk.img file
forces raw format (no auto-detection) for C<disk.img>.
- virt-cat --format=raw -a disk.img --format -a another.img
+ virt-cat --format=raw -a disk.img --format -a another.img file
forces raw format (no auto-detection) for C<disk.img> and reverts to
auto-detection for C<another.img>.