Xref: utzoo comp.unix.questions:31902 comp.unix.programmer:1973
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!decwrl!pa.dec.com!decprl!decprl!boyd
From: boyd@prl.dec.com (Boyd Roberts)
Newsgroups: comp.unix.questions,comp.unix.programmer
Subject: Re: How do I tell if STDIN is a PIPE?
Message-ID: <1991Jun3.150851.21915@prl.dec.com>
Date: 3 Jun 91 15:08:51 GMT
References: <1991May26.172328.713@arizona.edu> <1991May30.101153.27842@thunder.mcrcim.mcgill.edu> <653@eskimo.celestial.com> <1991Jun3.141144.23620@leland.Stanford.EDU>
Sender: news@prl.dec.com (USENET News System)
Reply-To: boyd@prl.dec.com (Boyd Roberts)
Distribution: world,local
Organization: Digital Equipment Corporation - Paris Research Laboratory
Lines: 26

In article <1991Jun3.141144.23620@leland.Stanford.EDU>, dkeisen@leland.Stanford.EDU (Dave Eisen) writes:
>
> >> In article <1991May26.172328.713@arizona.edu>, jjr@ace.ece.arizona.edu (Jeffrey J. Rodriguez) writes:
> >
> >     Try:
> >	fstat(0, &s);
> >	if(s.st_mode & S_IFIFO)
> >     ...
> 
> This doesn't work everywhere, in particular, it doesn't work on the machine I
> am posting from. s.st_mode & S_IFREG (which, by the way, is what you should
> be testing for) is 0 when stdin is a pipe. This doesn't seem to be consistently
> done across Unices.
> 

You don't test for anything that way.  This:

    if ((sb.st_mode & S_IFMT) == S_IFIFO)

is the way it's done (unless you have those gory POSIX macros).  But,
of course they're not `portable'; except to POSIX.


Boyd Roberts			boyd@prl.dec.com

``When the going gets wierd, the weird turn pro...''