sudo cp /KNOPPIX/dev/fb0 /dev/fb0 cp: writing `/dev/fb0': No space left on device
Removing was succesful, but as you can see copying wasn't. Now I have no /dev/fb0 at all!Ok. I got it back like it was. It seems that when I copied fb0 from /KNOPPIX it filled all available space and then reported about the unsufficient space. AFAIK all files in /KNOPPIX/dev aren't just regular files. They have no size and so on. So it would be actually impossible to copy those files. I belive I must somehow re-mount /KNOPPIX as read-write then chmod /KNOPPIX/dev/fb0 and then again re-mount /KNOPPIX to read-only.You can't remount KNOPPIX read-write because it is an iso9660 filesystem. The filesystem itself is read-only by design.
I can't think of any solution at the moment...i'll think about it.Instead of cp on character special file do this after the removal of the link /dev/fb0
sudo mknod /dev/fb0 c 29 0
This will re-create the "c" special file. Then be sure to chmod and chgrp per your requirements.
One other thing you might want to consider instead of removing and recreating /dev/fb0...
The group for /dev/fb0 is tty, add this group to user dsl and try your program