通过 powershell 将环境变量设置为依赖于 windows 上的其他环境变量

Question

I want to set a variable say JAVA_HOME to dynamically assume the value of another variable say JAVA_HOME_x64..such that whenever JAVA_HOME_x64 changes and a new terminal session is created JAVA_HOME gets assigned the value of whatever is value of JAVA_HOME_x64.

In powershell, I do following...

[System.Environment]::SetEnvironmentVariable('JAVA_HOME', '%JAVA_HOME_x64%', 'Machine');
[System.Environment]::SetEnvironmentVariable('JAVA_HOME_x64', 'c:\myjava', 'Machine');
[System.Environment]::GetEnvironmentVariable('JAVA_HOME', 'Machine') ==> returns %JAVA_HOME_x64% 

When I open a new command prompt and type set(or echo %JAVA_HOME%), it shows me value of JAVA_HOME as %JAVA_HOME_x64% and not c:\myjava.

However if i go to UI(as below) and manually edit(delete and recreate) JAVA_HOME and reset its value to %JAVA_HOME_x64%, and then when a launch a new command prompt/terminal session it now shows value of JAVA_HOME as c:\myjava..Why so? Any ideas? How to achieve the same behaviour as is in UI via PowerShell commands.

After some investigation i realize that, registry key(in Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment) created via above powershell command line for the said variable is of type REG_SZ, while the one created via UI is REG_EXPAND_SZ. This maybe the clue

Answer 1

The following worked..

Set-ItemProperty 'HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager\Environment' 'JAVA_HOME' '%JAVA_HOME_x64%' -Type 'ExpandString'

[System.Environment]::SetEnvironmentVariable('JAVA_HOME_x64','c:\program files\Zulu\jre','Machine')