Messages in this thread | | | Date | Fri, 12 Sep 1997 23:40:54 -0400 (EDT) | From | Tom Dyas <> | Subject | Re: how to tell if data is available for a file descriptor |
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On Fri, 12 Sep 1997, Jason Burrell wrote:
> Unless I'm missing something blatently obvious, NULL == 0, and thus this > manpage is nonsensical. "It may be zero, causing select to return > immediately. If timeout is NULL (no timeout), select can block > indefinately." How can it return immediately *and* block indefinately? > > I'm confused. I've never actually used select(), as odd as that may seem > to some. Well, not with indefinate or zero timeouts, anyway.
If the value of the passed pointer is 0 (a.k.a. NULL), then select() will block indefinitely. The "zero" refered to in the man page is the value contained within the fields of a passwd timeval strcuture. Thus, the pointer would be non-NULL and the fields tv_sec and tv_usec would be 0.
Tom
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