Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!virtech!cpcahil
From: cpcahil@virtech.uucp (Conor P. Cahill)
Newsgroups: comp.unix.questions
Subject: Re: Piping into Shell scripts
Summary: use tty(1)
Message-ID: <1990Feb28.142050.11607@virtech.uucp>
Date: 28 Feb 90 14:20:50 GMT
References: <2283@syma.sussex.ac.uk>
Reply-To: cpcahil@virtech.UUCP (Conor P. Cahill)
Organization: Virtual Technologies Inc., Sterling VA
Lines: 21

In article <2283@syma.sussex.ac.uk> andy@syma.sussex.ac.uk (Andy Clews) writes:
>Is there any way of getting a Shell script (C or Bourne) to recognise
>whether it is receiving input from a pipe?

tty(1) will report "not a tty" if it's input is not from a tty. 

So the following should work:

	testdata="`tty`"
	if [ "$testdata" = "not a tty" ]; then
		echo "we are not running from a terminal.  therefore we must"
		echo "be running from a pipe or with stdin redirected from a" 
		echo "file of some sort (of course, it also could be closed)"

		exit
	fi
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| Conor P. Cahill     uunet!virtech!cpcahil      	703-430-9247	!
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