KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q110305: INFO: Windows NT Reads Environment Variables from AUTOEXEC.BAT

Article: Q110305
Product(s): Microsoft C Compiler
Version(s): 1.0,1.5,2.0,4.0,5.0,6.0,6.11
Operating System(s): 
Keyword(s): kbVC100 kbVC200 kbVC400 kbVC500 kbVC600
Last Modified: 27-JUL-2001

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual C++, versions 1.0, 1.5, 2.0, 4.0 
- Microsoft Visual C++, 32-bit Enterprise Edition, versions 5.0, 6.0 
- Microsoft Visual C++, 32-bit Professional Edition, versions 5.0, 6.0 
- Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
- Microsoft Macro Assembler (MASM), version 6.11 
- Microsoft Fortran Powerstation 32 for Windows NT, version 1.0 
-------------------------------------------------------------------------------

SUMMARY
=======

At boot time, Windows NT reads the AUTOEXEC.BAT file and sets any environment
variables that do not conflict with Windows NT settings. These environment
variables may affect the way some programs work.

MORE INFORMATION
================

Environment variables may be used to set compiler, assembler, and linker
options. Settings made in this way will override settings made in the Visual
Workbench and in makefiles. For example, the following setting will cause the
compiler to pack structures on 1-byte boundaries, and this can cause problems
when creating applications for Windows NT using Visual C++ 32-bit edition:

  SET CL=-Zp1

The following environment variables may affect development tools:

  CL       : C/C++ compilers
  ML       : MASM
  FL32, FL : FORTRAN compilers
  LINK     : Link

Environment variables set in AUTOEXEC.BAT can only be seen in a console session.
To see the current environment variable settings, run a console session and
enter the following command at a prompt:

  set

The resulting list may include variable settings that do not show up when
checking the system settings in the Control Panel. These variables are probably
being set in the AUTOEXEC.BAT file.

To prevent problems related to setting of unwanted environment variables in
Windows NT, but to still allow them to be set when booting MS-DOS on a dual-
boot machine, use a secondary batch file. For example, place all of the SET
commands in the AUTOEXEC.BAT file in a file called DOSVARS.BAT. Save this file
in the root directory of your boot drive (the same directory as AUTOEXEC.BAT).
Add a line to execute this batch file to the end of AUTOEXEC.BAT (add it as the
last line):

     DOSVARS

This will execute the batch file to set the variables and not return to the
AUTOEXEC.BAT processing. You can also use the following

     CALL DOSVARS

at any point in the AUTOEXEC.BAT file so that processing of AUTOEXEC.BAT
continues after the settings are made. Because Windows NT does not process
nested batch files when reading AUTOEXEC.BAT, the variables will be set for DOS
but not for Windows NT.

Additional query words: MASM FORTRAN

======================================================================
Keywords          : kbVC100 kbVC200 kbVC400 kbVC500 kbVC600 
Technology        : kbVCsearch kbVC400 kbMASMsearch kbAudDeveloper kbFortranSearch kbvc150 kbvc100 kbZNotKeyword2 kbMASM611 kbVC500 kbVC600 kbVC200 kbFORTRANPower32100NT kbVC32bitSearch kbVC500Search
Version           : :1.0,1.5,2.0,4.0,5.0,6.0,6.11

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.