Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!unmvax!pprg.unm.edu!hc!lll-winken!uunet!portal!atari!kbad
From: kbad@atari.UUCP (Ken Badertscher)
Newsgroups: comp.sys.atari.st
Subject: Re: setenv on boot-up (how?)
Summary: TOS does not have a unique environment variable format.
Keywords: environment, standards
Message-ID: <1407@atari.UUCP>
Date: 27 Mar 89 00:27:57 GMT
References: <747@stag.UUCP>
Reply-To: kbad@atari.UUCP (Ken Badertscher)
Organization: Atari Corp., Sunnyvale, CA
Lines: 34


Dale posts some very useful code for dealing with environment variables.
However, the part of the code that deals with the TOS environment will
hopefully be obsolete very soon.  The fact that there is a null after
the PATH= in the default TOS environment string is an anachronism left
over from a bug in earlier TOS versions, to wit; the BIOS variable which
holds the value of the boot device was used as a WORD instead of as
a BYTE when filling the startup environment string, hence you get a null
before the drive letter.
  This is not standard, nor should it be construed as a "TOS" format
environment.  The easiest way to check for the default environment is
with a couple of longword compares (look for "PATH" then
"=;\0<bootdev>" <- really four characters there, =, ;, <null>, A or C  ).
GEMDOS environment strings are:
	...a series of null-terminated strings of the format
	"VAR=value"; the last string is followed by two zero
	bytes, indicating the end of the environment.
						- Pexec Cookbook
Which is to say, they follow the somewhat universal environment string
standard, a'la UNIX(tm) or MS-DOS(tm).  The fact that semicolons were
required to separate path names was an oversight as well; TOS 1.4 allows
commas or semicolons to separate pathnames in the PATH environment
variable. In fact, the AES now uses the environment much more
intelligently, and will look down whatever paths you have specified for
shel_find and rsrc_load calls.
 
   Hopefully someday I'll get to release the auto/accessory environment
setting utility that I've written; I think people will like being able
to stick their resources all in one folder...

-- 
 Ken Badertscher                 | #include <disclaimer>
 Atari R&D Software Engine       | GEMDOS LIVES! ...or is that Frodo?
 {portal,ames,imagen}!atari!kbad | I can never remember these things...