From: Smelly Pooh (plop at domain redbrick.dcu.ie)
Date: Tue 18 Jul 2000 - 19:44:32 IST
In reply to Caolan McNamara's flatulent wordings,
> Funny how you get blind spots about various things, was discussing
> file descriptors and have been assuming for ages that a newly execed
> program got a completely new set of such resources. But on reading the
> sun man page I was enlightened.
> After a fork both parent and child have the same fds, after an exec
> the new process *still* has the same open fds (as long as fcntl with ,
> FD_CLOEXEC to close them on exec isnt set). Enter crash tolerant stuff...
Well, think about stuff like inetd, which listens on sockets and forks/execs
various daemons when it gets a connection, socket fd needs to be preserved
there. Even for something as simple as a unix pipe, foo | bar at the syscall
level it would involve a call to pipe, fork, dupping output FD to stdout on
first process, dup input FD to stdin on second process, then exec foo and exec
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