如何从C＃执行DOS SET命令并在exe关闭后保持变量？

Question

I have a C# console executable started within a DOS command process.

I need to be able to execute DOS commands from the C# executable (specifically I need to be able to SET variables) and have the variables persist such that the rest of the DOS process can reference them.

ie:

Start DOS process -> C# executes a SET command to set UserVariable -> DOS process can ECHO %UserVariable%

Due to performance reasons I cannot write the set command to a dos script. In fact, I cannot have any file I/O at all.

Can anyone help?

Answer 1

SETX persists the environment variables. Check this: http://technet.microsoft.com/es-es/library/cc755104(v=ws.10).aspx

Answer 2

The problem isn't with the fact that you are calling SET from within a C# application. Even if you open a windows prompt and call SET to set a user variable, it will not persist through sessions.

Display, set, or remove CMD environment variables. Changes made with SET will remain only for the duration of the current CMD session.

Source .

I advise you to set variables directly through .Net, anyway. You can use Environment.SetEnvironmentVariable to do this.

Answer 3

Use the following .NET method instead:

Environment.SetEnvironmentVariable

Answer 4

If you are running a C# app from a dos script and wishing to use variables set in the app afterwards from the script, I don't know how to do that for just the context of that script from within C#, the other answers here show you for the machine itself but I appreciate you need something with a less permanent scope.

A meta-programming workaround this could be to:

• Call the C# app from a DOS FOR loop
• From the C# app, output to the console SET commands
• Use the for loop to execute the app output

The calling DOS script would look like this:

FOR /F "tokens=* delims=" %%A IN ('MyApp.exe') DO ( 
   %%A
)

The Console output from MyApp.exe would need to be in the form:

SET UserVariable1=UserValue1
SET UserVariable2=UserValue2

And then each of the output lines would be executed by the calling FOR loop and the variables would then exist in the context of the calling script.

Answer 5

This is by no means an answer, but with the nature of the problem this "compromise" is the path we have chosen for the time being.

We'll be using a batch script created by the C# application which will have all the simple set commands needed which will then be executed by the CMD process that invoked the C# application.

Please feel free to add any further ideas and comments as this is not the ideal solution.

Answer 6

Unfortunately, so far as I can tell, this is the "solution" that is available, through at least Windows 7. I've been experimenting with various ways to set and subsequently use environment variables, and the bottom line of my research is that, if you want to use a variable, it must either be set in advance into the USER or MACHINE key, or it must be a local variable, set by script command, then tested further along in the same script.

So far as I am concerned, the third element in that enumeration, Process, is essentially useless. The only way that I can see that it might be useful is if a process spawns another process, passing its environment to the child process. That's overkill for most run-of-the-mill administrative scripts.