Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!virtech!cpcahil
From: cpcahil@virtech.uucp (Conor P. Cahill)
Newsgroups: comp.lang.c
Subject: Re: Sticky IBM C programming problems (summary of replies)
Message-ID: <1990Mar2.131501.23297@virtech.uucp>
Date: 2 Mar 90 13:15:01 GMT
References: <90055.142524CMH117@psuvm.psu.edu> <9003012109.AA07700@ei.ecn.purdue.edu>
Reply-To: cpcahil@virtech.UUCP (Conor P. Cahill)
Followup-To: comp.sys.ibm.pc
Organization: Virtual Technologies Inc., Sterling VA
Lines: 26

In article <9003012109.AA07700@ei.ecn.purdue.edu> tlmfe@EE.ECN.PURDUE.EDU (Mark B Strong) writes:
>
>Quick question:  Why won't an environmental variable I change within
>a C program stay after the program is terminated?  Setenv() doesn't seem
>to work?  

First of all, this isn't a C questions it is an OS question so I have forwarded
followups to comp.sys.ibm.pc

The answer is that a programs environmental variables are stored in that
program's data space is are lost when the program exits.  The only thing
special about environment variables is that there exists a convention for
passing that portion of your data space to all child processes, but you cannot
use it to change the data space of a parent process (which is what you are
apparently trying to do).

Of course, your program could pass the environment variable changes back
through a file descriptor (say stdout) and the parent program could 
make these changes in it's environment.  But you will have to modify both
programs to do this.

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