Save off env: drive and later revert

Question

I am running multiple scripts from the powershell console. These scripts add/modify variables in the env: drive. Between running each script, I would like to reset the env: drive to what it was when I opened up the console. Is there a way to save off/copy the env: drive, and then copy it back at a later point?

Answer 1

The easiest way is to just start another process for each script. Instead of

.\foo.ps1

just use

powershell -file .\foo.ps1

Then each script gets its own process and thus its own environment to mess with. This doesn't work, of course, if those scripts also modify things like global variables you'd rather have retained in between.

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On the other hand, saving the state of the environment is fairly simple:

$savedState = Get-ChildItem Env:

And restoring it again:

Remove-Item Env:*
$savedState | ForEach-Object { Set-Content Env:$($_.Name) $_.Value }

Answer 2

You might want to take a look at the PowerShell Community Extensions module. There commands that make managing environment variables easier to do. In particular, Push-EnvironmentBlock and Pop-EnvironmentBlock are useful here. "Push" saves the current environment variables and pushes it onto a stack. "Pop" removes the previous state from the stack and restores it. So you would probably do this

Push-EnvironmentBlock -Description "Before running script.ps1"
.\script.ps1
Pop-EnvrionmentBlock