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Setting "Volatile" Environment Variables

Posted on 2009-06-30
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Is there a shell / Dos command that can be used to set a current session only, "volatile" environment variable?

Mike

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Question by:shacho
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6 Comments
 
LVL 96

Expert Comment

by:Lee W, MVP
ID: 24751591
What do you mean by "volatile" - give an example.

(The SET command should set any environment variable you want for the duration of the command prompt).
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LVL 66

Expert Comment

by:johnb6767
ID: 24751652
top of the script....

setlocal

and at the end.....

endlocal
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Expert Comment

by:AmazingTech
ID: 24752404
You'll probably need to use a vbscript file to add in the volatile envrionment variable.

After it's added start a new command prompt.

Your question should be worded as:

Is there a shell / Dos command that can be used to for the current user's logged on session only, i.e setting the "volatile" environment variable?
set shell = WScript.CreateObject("WScript.Shell")
set volatile = shell.Environment("VOLATILE")
volatile("VarName") = "Var Value"

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Author Comment

by:shacho
ID: 24791511
I understand and frequently use the VBScript approach AmazingTech described, but I am not terribly familiar with shell scripting so please bear with me if this question sounds nonsensical.  The goal here is to create an Environment Variable of the "Volatile" flavor named "PATH" that exposes the location of a dll long enough for a subsequently loaded application to see it.  The way I am doing this now is precisely as AmazingTech describes.  However, this approach has a pitfall; the script has to run its course and exit before the variable is exposed to the application.  Setting up the variable and launching the app within the same script does not work.  So I was thinking that perhaps if I tried to achieve this with a batch file instead of a VBScript, my results would be different, so I was inquiring about the syntax.  Set and Setlocal as far as I can tell dimension and fill variables for the batch file to use - but I don't really understand the relationship between these variables and the "Environment Variables" that are accessible via the Windows GUI or the WScript.Shell methods.  Since "Set" with no parameters reveals in the shell them there is clearly some relationship, but I don't know what it is.  Can you help me understand this?

Mike
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LVL 96

Accepted Solution

by:
Lee W, MVP earned 2000 total points
ID: 24792218
If you're trying to add to the path statement, then a simple batch file of:

@echo off
set path=%path%;x:\path\to\your\file.dll
start "" x:\path\to\your\application.exe


Variables set in command prompts "reset" upon exiting the command prompt and only apply to that command prompt - unless you use something like setx
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Author Comment

by:shacho
ID: 24902559
Thanks for your comments.

Mike
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