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From: jeff@quark.WV.TEK.COM (Jeff Beadles)
Newsgroups: comp.unix.shell
Subject: Re: Yet Another bourne shell query
Message-ID: <8478@orca.wv.tek.com>
Date: 31 Aug 90 14:59:35 GMT
References: <437@minya.UUCP>
Sender: news@orca.wv.tek.com
Reply-To: jeff@quark.WV.TEK.COM (Jeff Beadles)
Organization: Tektronix, Inc., Wilsonville, OR
Lines: 29

jc@minya.UUCP (John Chambers) writes:
>I basically want to write something like:
>	if [ <file 0 is open> ];then exec</dev/null;fi
>but I don't know what to put between the [ and the ].  Any ideas?
>Is it possible?  Or should I just rewrite the scripts in C?

Well, from the test(1) man page...

     -t [ fildes ]
               True if the open file whose file descriptor number
               is fildes (1 by default) is associated with a
               terminal device.

This, you can tell if a file descriptor is attached to a terminal.  (It will
fail for a pipe or redirection)

Thus, something like this might be what you are looking for:

if [ -t 0 ] ; then
	exec </dev/null
fi

Best of luck,

	-Jeff
-- 
Jeff Beadles				  jeff@quark.WV.TEK.COM 
UTek Network Engineering, Tektronix Inc.  +1 503 685 2568
			SPEEA - Just say no.