The following code does not return "Y" as expected. Only in the next session (another new window) it works? I would expect it to be available immediately?
[Environment]::SetEnvironmentVariable("X", "Y", "Machine")
Write-Host $env:X
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2 Answers
You must do this since the process gets env vars on start, not while running (i.e. you would have to restart shell for this to work your way):
[Environment]::SetEnvironmentVariable("X", "Y", "Machine")
$Env:X = "Y"
There is also a way to broadcast this to other windows using WM_SETTINGCHANGE
To effect a change in the environment variables for the system or the user, broadcast this message with lParam set to the string "Environment".)
# Notify system of change via WM_SETTINGCHANGE
if (! ("Win32.NativeMethods" -as [Type]))
{
Add-Type -Namespace Win32 -Name NativeMethods -MemberDefinition @"
[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
public static extern IntPtr SendMessageTimeout( IntPtr hWnd, uint Msg, UIntPtr wParam, string lParam, uint fuFlags, uint uTimeout, out UIntPtr lpdwResult);
"@
}
$HWND_BROADCAST = [IntPtr] 0xffff; $WM_SETTINGCHANGE = 0x1a; $result = [UIntPtr]::Zero
[Win32.Nativemethods]::SendMessageTimeout($HWND_BROADCAST, $WM_SETTINGCHANGE, [UIntPtr]::Zero, "Environment", 2, 5000, [ref] $result) | out-null
}
Comments
As far as I know, a process loads the environment variables only once (at start). But you can change it using:
[Environment]::SetEnvironmentVariable("X", "Y", "Process") # for the current session
Note: You probably want to set both:
[Environment]::SetEnvironmentVariable("X", "Y", "Machine")
[Environment]::SetEnvironmentVariable("X", "Y", "Process")
