Chaining Parent PSP Environment Variables

ID: Q96209

3.10 3.50 3.51 4.00 WINDOWS NT kbprg

The information in this article applies to:

Microsoft Win32 Application Programming Interface (API) included with:
```
    - Microsoft Windows NT versions 3.1, 3.5, 3.51 and 4.0
```

SUMMARY

Some MS-DOS-based applications change the environment variables of their parent application by chaining through the program segment prefix (PSP). With Windows NT, this functionality doesn't work if the parent is a Win32-based application.

MORE INFORMATION

When an MS-DOS-based application is started from a single command shell (SCS), the application inherits a new copy of the environment variables. Any attempts by the MS-DOS-based application to modify its parent's environment variables will not work. When the MS-DOS-based application exits, the SCS will be "restored" to its original state. If another MS-DOS-based application is started, the second application will receive the same environment that the first MS-DOS-based application received.

If an MS-DOS-based application (B) is spawned by another MS-DOS-based application (A), any modifications to application A's environment variables will be reflected when application B exits.

For more information on how environment variables are set, please see the following article(s) in the Microsoft Knowledge Base:

   ARTICLE-ID: Q100843
   TITLE     : Environment Variables in Windows NT

KBCategory: kbprg KBSubcategory: BseMisc Additional reference words: 3.10 3.50 3.51 4.00

Keywords          : kbnokeyword kbKernBase kbGrpKernBase 
Version           : 3.10 3.50 3.51 4.00
Platform          : NT WINDOWS

Last Reviewed: December 18, 1996