Xref: utzoo comp.unix.questions:11943 comp.unix.xenix:5165
Path: utzoo!attcan!uunet!auspex!guy
From: guy@auspex.UUCP (Guy Harris)
Newsgroups: comp.unix.questions,comp.unix.xenix
Subject: Re: How to determine file being redirected to in C
Keywords: redirection
Message-ID: <1104@auspex.UUCP>
Date: 1 Mar 89 20:13:06 GMT
References: <10@sherpa.UUCP> <7419@pyr.gatech.EDU>
Reply-To: guy@auspex.UUCP (Guy Harris)
Distribution: na
Organization: Auspex Systems, Santa Clara
Lines: 10


 >You may want to investigate the isatty() function call.  I believe that
 >you can use something like:  isatty(stdout)  which will tell you if
 >standard out is going to a terminal (the usual case), or if it has been
 >redirected via a pipe or into a file.

We've been here before.  No, "isatty(stdout)" won't tell you anything of
the sort.  "isatty" takes a file descriptor, *not* a standard I/O
"FILE *".  "isatty(fileno(stdout))", or "isatty(1)", will tell you
whether the standard output is a tty or not.