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From: carl@CITHEX.CALTECH.EDU (Carl J Lydick)
Newsgroups: comp.os.vms
Subject: Re: VMS C SYS$OUTPUT
Message-ID: <870912025526.02e@CitHex.Caltech.Edu>
Date: Sat, 12-Sep-87 06:01:44 EDT
Article-I.D.: CitHex.870912025526.02e
Posted: Sat Sep 12 06:01:44 1987
Date-Received: Sun, 13-Sep-87 09:38:22 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 25


 > I have been using VAX C version 2.3 to write a program designed to be run
 > as a detached process.  It runs fine, but VAX C insists on opening
 > SYS$OUTPUT and SYS$ERROR even though the program does not do any output.
 > There are no Output functions used in the program and when I run it /detached
 > it creates files called SYS$OUTPUT. and SYS$ERROR.  Is there a way around
 > this? Is main() doing this? I can close the files with fclose(stdout) and
 > fclose(stderr) but that still leaves me with useless files in my directory.

Well, yes and no.  In order to achieve at least partial compatibility with
that other operating system (U*IX. to avoid a footnote) the VAX C compiler
likes to have the three U*IX standard files open.  It does this in the
following way:
	If it sees a routine called "main" as the first routine in a module
it compiles, it has "main" call "C$MAIN"  before it does anythhing else.
C$MAIN takes care of parsing the command line and opening the standard files.;

 > So it seems that stdout and stderr are opened by default (which makes sense
 > for interactive processes, but I need to find a way to prevent them from
 > being opened.

As you may have gathered from the above, the way to avoid this unfortunate
(in a few cases; one that comes immediately to mind is a print symbiont)
state of affairs, just don't have a "main" routine.  Bear in mind that this
also means you've got to parse the command line yourself.