Checking if the other end of a fifo is open

[Nicholas Leippe]

On Thu Apr 9 2009 14:48:09 Dave Smith wrote:
> Nicholas Leippe wrote:
> > An opposite timeout approach could be:
> >
> > 1) set a flag
> > 2) create a trap handler that clears the flag
> > 3) do your write in backgrounded subshell, that signals the parent when
> > finished
> > 4) after spawning the subshell, sleep (your timeout)
> > 5) then check the flag
>
> I think I'll try this out. How do I send a signal to the parent from the
> subshell? kill? Do I need to pass the parent pid to the subshell somehow?

kill -USR1 # should do it

$$ # has the pid of the current process--just pass that in to the child