Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!wuarchive!mit-eddie!bloom-beacon!vaxeline!paul
From: paul@vaxeline.COM (Paul Selkirk)
Newsgroups: comp.os.msdos.programmer
Subject: Re: Command.com and a message
Message-ID: <1274@vaxeline.COM>
Date: 6 Dec 90 01:53:32 GMT
References: <67560@unix.cis.pitt.edu> <5648@uafhp.uark.edu>
Reply-To: paul@vaxeline.ftp.com.UUCP (Paul Selkirk)
Organization: FTP Software, Inc.
Lines: 20

You could keep users from reloading your program in the following way: Set
an environment variable to indicate that you've spawned a DOS shell.
	putenv("SHELL=yes"); 

In the initialization code for your program, test for the presence of this
variable, and abort with an message if it's found.
	if (getenv("SHELL")) { 
		puts("Type EXIT to get back to FUTURE"); 
		exit(1); 
		}

Since the variable is only in the environment of your program an programs
that it spawns (command.com), it goes away when you exit, so the user never
has to know about it.

Epsilon does it this way, and I heartily approve.

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Paul Selkirk                                                   paul@ftp.com 
FTP Software                           26 Princess St., Wakefield, MA 01880