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From: fuss@rocksanne.UUCP (William Fuss)
Newsgroups: comp.unix.questions
Subject: distinguishing from pipes and files
Message-ID: <454@rocksanne.UUCP>
Date: Sat, 21-Nov-87 02:30:51 EST
Article-I.D.: rocksann.454
Posted: Sat Nov 21 02:30:51 1987
Date-Received: Mon, 23-Nov-87 04:20:39 EST
Reply-To: fuss@rocksanne.UUCP (William Fuss)
Organization: Xerox Corp., Webster, NY
Lines: 39
Keywords: files, pipes


Seeing how there has been a lot of discussion about pipes....
I would like to know the following:

Can a process can recognize the "source" of its input/output ???
for example, given the scenerio below:

	(1)
		foo < input > file2 &
		bar < file2 > file3 &
		foobar < file3 > output &

	(2)
		cat input | foo | bar | foobar > output

Can "bar" figure out that its standard input is coming from:

	a file in example (1),
		vs
	a pipe in example (2),

or does the shell take care of things such that they look the same?


Any ideas?  Any clues?
or am I digging a hole that cannot be dug?

Any *useful* advice/comments/... appreciated.
Please respond via email.

Thanks,

billfuss	...!rochester!fuss.wbst@xerox.COM
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