INF: How to Modify the Environment for a Spawned Process

ID Number: Q11997

3.00 4.00 5.00 5.10 6.00 6.00a 6.00ax 7.00 | 5.10 6.00 6.00a

MS-DOS | OS/2

Summary:

This article discusses how to modify the PROMPT environment variable

in a spawned process with Microsoft C versions 5.0, 5.1, 6.0, 6.0a,

6.0ax, and C/C++ version 7.0. Use this as a guide to modify any

environment variable in a spawned process.

More Information:

Because PROMPT is an MS-DOS and OS/2 environment variable, you just

need to set your own value for PROMPT in the spawned process's

environment. C allows you to specify the environment to be handed to a

child process in one of the following two ways:

- Use one of the spawn*e() functions. See the C run-time library

reference or online help supplied with your compiler for specific

details about the spawn() family of functions.

- Use the putenv() function to modify the program's own local copy of

the environment, then use one of the spawn() functions other than

spawn*e(). Details on the putenv() function may also be found in

the C run-time library reference or online help.

In general, a process may only alter the environment to be handed to a

child process. The C run-time library functions give the illusion of

being able to alter the environment space but this is accomplished by

making a copy of the environment strings during start up and,

thereafter only altering this copy.

Additional reference words: 5.00 5.10 6.00 6.00a 6.00ax 7.00