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Q11997: HOWTO: Modify the Environment for a Spawned Process

Article: Q11997
Product(s): Microsoft C Compiler
Version(s): MS-DOS:6.0,6.00a,6.00ax,7.0; OS/2:5.1,6.0,6.00a; WINDOWS:1.0,1.5; WINDOWS NT:1.0,2.0,4.
Operating System(s): 
Keyword(s): kbCRT kbVC kbVC100 kbVC200 kbVC400 kbVC500 kbVC600
Last Modified: 10-MAY-2001

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The information in this article applies to:

- The C Run-Time (CRT), included with:
   - Microsoft C for MS-DOS, versions 6.0, 6.0a, 6.0ax 
   - Microsoft C for OS/2, versions 5.1, 6.0, 6.0a 
   - Microsoft C/C++ for MS-DOS, version 7.0 
   - Microsoft Visual C++ for Windows, 16-bit edition, versions 1.0, 1.5 
   - Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 4.0, 5.0, 6.0 
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SUMMARY
=======

The text below discusses the process through which an application can modify the
PROMPT environment variable in a spawned process. Use the same procedure to
modify any environment variable in a spawned process.

PROMPT is an environment variable used by MS-DOS, OS/2, and Windows NT. To change
the value for the PROMPT environment variable, use one of the following two
methods to specify the environment in which a child process runs.

- Use one of the spawn*e() functions. See the run-time library reference manual
  or the online help file provided with your compiler for specific information
  about the spawn() family of functions.

- Use the putenv() function to modify the environment in which your application
  executes, then start the child process with one of the spawn() functions. See
  the run-time library reference manual or the online help file provided with
  your compiler for specific information about the putenv() function.

In general, a process can alter only the environment in which a child process
will run. The C run-time library functions simulate the ability to alter the
environment space in which the current process runs by making a copy of the
environment when the process starts up and allowing the process to modify the
copy of the environment.

Additional query words:

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Keywords          : kbCRT kbVC kbVC100 kbVC200 kbVC400 kbVC500 kbVC600 
Technology        : kbVCsearch kbAudDeveloper kbCRT
Version           : MS-DOS:6.0,6.00a,6.00ax,7.0; OS/2:5.1,6.0,6.00a; WINDOWS:1.0,1.5; WINDOWS NT:1.0,2.0,4.0,5.0
Issue type        : kbhowto

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