On 10/05/2015 00:07, Guillermo wrote:
I ran into this while experimenting with the example / template stage 1 and 3 init scripts that come with s6's source code. Both of them do an early fdclose 0 to ignore input. Wouldn't that be tempting the demons to fly through your nose, then? :)
Know that I precisely audited the whole series of programs running with 0, 1 and 2 closed in those stages before answering you. And there's no risk there, it works. :) (In stage 3, you can replace "fdclose 0" with "redirfd -r 0 /dev/null" and it will be conformant. No such easy way out in stage 1, though, if you want to change /dev after the kernel has mounted it. Note that you don't have to do that if you're using devtmpfs and keeping it.)
Anyway, I had either replaced the early fdclose 0 with redirfd -r 0 /dev/null (and also realized that worked by accident, because I somehow have a nonempty /dev at startup) or delayed it a bit. I suppose that's good enough...
Did you really manage to umount /dev (maybe) and mount a tmpfs over it (for sure) with fds still open to the old /dev ? Without an EBUSY error ? If it's the case, and you're using Linux, then the kernel's behaviour changed. -- Laurent
