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From: psfales@ihlpe.ATT.COM (Pete Fales)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Environment settings from a C program
Message-ID: <2168@ihlpe.ATT.COM>
Date: Mon, 12-Oct-87 11:00:42 EDT
Article-I.D.: ihlpe.2168
Posted: Mon Oct 12 11:00:42 1987
Date-Received: Tue, 13-Oct-87 06:50:45 EDT
References: <700@hsi.UUCP> <114@fxgrp.UUCP>
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 64
Keywords: ms-dos environ putenv getenv turboc

In article <114@fxgrp.UUCP>, ljz@fxgrp.UUCP (Lloyd Zusman) writes:
> In article <700@hsi.UUCP> mark@hsi.UUCP (Mark Sicignano) writes:
> >I am trying to change an environment variable from within 
> >a Turbo-C program.  Turbo-C provides a function, putenv()
> >which will make changes to, add, or delete environment,
> >but any changes are made to the environment within the program,
> >and for child processes.
> >
> >I need for these changes to remain.  Is it possible?
> 
> 
> Sorry, but what you want to do isn't possible.  DOS (be it MSDOS or PCDOS)
                                 ^^^^^^^^^^^^^^
> is written such that no running program can change the environment of its
> parent.  In case you need more explanation, consider this:
> 

This is rather strong language for an operating system with no memory
protection.  I have 512 byte program downloaded from a bulletin board
called SETVAR.COM that does exactly that.  You type SETVAR XXX and
one line of standard input is put into XXX in the PARENT environment.  I
don't know how it works, but it is really nifty.  It provides
many of the same functions as back-quote substitution under UNIX.

Since the file is small, and news won't let me post this article
without more text, here is the uuencoded SETVAR.ARC.

begin 644 SETVAR.ARC
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M&AH:&AH:&AH:&AH:&AH:&AH:&AH:&AH:&AH:&AH:&AH:&AH:&AH:&AH:&AH:
4&AH:&AH:&AH:&AH:&AH:&AH:&AH:
 
end
-- 
Peter Fales		UUCP:	...ihnp4!ihlpe!psfales
			work:	(312) 979-7784
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