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From: jsdy@hadron.UUCP (Joseph S. D. Yao)
Newsgroups: net.unix-wizards
Subject: Re: am I in background?
Message-ID: <77@hadron.UUCP>
Date: Sat, 16-Nov-85 16:35:19 EST
Article-I.D.: hadron.77
Posted: Sat Nov 16 16:35:19 1985
Date-Received: Mon, 18-Nov-85 07:58:12 EST
References: <129@wgivax.UUCP>
Reply-To: jsdy@hadron.UUCP (Joseph S. D. Yao)
Organization: Hadron, Inc., Fairfax, VA
Lines: 17

In article <129@wgivax.UUCP> mo@wgivax.UUCP (Michael O'Shea) writes:
>On a 4.2 system, is there any reliable way in which a c-program can determine
>from within itself if it is running in background and/or has its input and/or
>output redirected (from/into a file or through a pipe)?

It sounds (from text not quoted here) like what you really want to know
is whether the standard input is the user's terminal.  Phrased that
way, you've prob'ly already realised the easy way:

#define STDIN	0

	if (isatty(STDIN)) ...

(See man 3 ttyname on BSD4.2; should be similar on all other Unices.)
-- 

	Joe Yao		hadron!jsdy@seismo.{CSS.GOV,ARPA,UUCP}