0

When I change any environment variable in Windows using GUI (System Properties/Environment Variables/System Variables) changes are reflected immediately in cmd terminal, but PowerShell shows an old value.

Here cmd recognized that I changed JAVA_HOME value from C:\Users\nikif\.jdks\openjdk-19.0.1 to C:\Users\nikif\.jdks\corretto-16.0.2

enter image description here

PowerShell still shows the previous value - C:\Users\nikif\.jdks\openjdk-19.0.1 enter image description here

Is there any command that will make PowerShell recognize the environment variable change made in GUI? Or maybe there is a better way to change the environment variable from PowerShell?

Thank you.

Improve this question
3
  • Sometimes a system restart will do. Commented Dec 27, 2022 at 8:29
  • What do you mean by "recognized"? Without restarting the CMD.EXE or PowerShell.exe session? And where (and how) exactly do you change the JAVA_HOME variable (from Computer/Properties/Environment)? Commented Dec 27, 2022 at 8:36
  • There are 3 sets of env variables: system, user, process. The 'process' set is created from the 2 others when the process starts. You can read the values in 'user' and 'system' with [Environment]::GetEnvironmentVariable('JAVA_HOME','Machine') (for system) or ..., 'User') for (user). Programs can intercept the WM_SETINGCHANGE message to update the 'process' set of environment variables. But the program must decide what rules should apply for this update. e,g, Should it delete variables in the 'process' set? This could be dangerous in a shell like cmd or PowerShell. Commented Dec 27, 2022 at 8:58

1 Answer 1

Reset to default
2

This all should really be a comment (I tried above), but attempting to explain why the question, as it stands, is too vage requires just more explaination.

Processes get their environment when started by the OS. They basically get a copy the environment as it was at that point in time. When you start a process you can (using the respective APIs) pass additional or altered environment variables.

During the existance (runtime) of a process you cannot change the environment. Shells are a common exception, as they provide specific syntax that does that (set NAME=VALUE in CMD.EXE and $env:NAME="VALUE" in PowerShell, for example). An application itself could also do such stuff from its code using respective APIs. But in general, there is no way to change variables from the outside.

One process will never see the changes done to the environment in a different process. For example, if you have to separate CMD.EXE sessions running and change a variable in one of them, the other will not know. The environment is private to each process.

A potential exception is the (global/system) environment variables you can set using the Computer/Properties/Environment setting (applet). The system will send a WM_SETTINGCHANGE window message indicating the that environment has changed. Applications can register to this message and act accordingly.

However, neither PowerShell nor CMD.EXE do seem to listen to this message (it would require a (hidden) Window anyway and both are console applications). And frankly, it would be not good if they did. Consider CMD.EXE just execuing a batch file and a variable (say PATH) changes underneath - security issues and general havoc all over.

Improve this answer
Sign up to request clarification or add additional context in comments.

1 Comment

Thank you for the answer. I understand that I need to restart the terminal to see the changes. For some reason, I thought that even if I restarted PowerShell I didn't see changes in environment variables. Tried again and it works. Anyway, I think your answer will be helpful for other people.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.