C# PowerShell Script not working with ExecutionPolicy

Question

I´m trying to run a PowerShell script with C# on .netCore.

I have tried many different solutions for now, but none of them seem to work. I just want to execute a PowerShell script and set ExecutionPolicies and Scope to make it work. But I always got the exception that the ExecutionPolicies don´t allow me to run the script that way.

Despite that with the actual configuration and code, you find below, I don´t get any feedback from the Debugger after reaching the point where .Invoke(); is executed. And waiting for response and letting the software doing its stuff in background leads always to a stackoverflow exception.

commandParameters is a simple Dictionary<string, string>

Any thoughts on this?

Cheers.

---

var iss = InitialSessionState.CreateDefault2();
        // Set its script-file execution policy.
        iss.ExecutionPolicy = Microsoft.PowerShell.ExecutionPolicy.Unrestricted;
        iss.ExecutionPolicy = (ExecutionPolicy)Microsoft.PowerShell.ExecutionPolicyScope.CurrentUser;

        // Create a PowerShell instance with a runspace based on the 
        // initial session state.
        PowerShell ps = PowerShell.Create(iss);

 ps.AddCommand(path + "\\" + fileName);
        ps.AddParameters(commandParameters);
        var results = ps.InvokeAsync().GetAwaiter().GetResult();

Answer 1

• Assigning to iss.ExecutionPolicy only ever controls the execution policy for the current process.

• Do not assign a Microsoft.PowerShell.ExecutionPolicyScope value, as it is an unrelated enumeration that defines the execution-policy scope, relevant only to the Set-ExecutionPolicy and Get-ExecutionPolicy cmdlets. The numeric values of this unrelated enumeration just so happen to overlap with the appropriate [Microsoft.PowerShell.ExecutionPolicy] enumeration values, so that policy scope CurrentUser maps onto policy RemoteSigned (value 0x1).

  • In effect, your second iss.ExecutionPolicy = ... assignment overrides the first one and sets the process-scope execution policy to RemoteSigned.
  • The process-scope execution policy, i.e. for the current process only, is the only one you can set via an initial session state; see the next section for how to change policies for persistent scopes.

Therefore, iss.ExecutionPolicy = Microsoft.PowerShell.ExecutionPolicy.Unrestricted; alone is enough to invoke *.ps1 files in the session at hand - remove the second iss.ExecutionPolicy = ... assignment.

---

If you want to modify the execution policy persistently, you must use .AddCommand('Set-ExecutionPolicy') with the appropriate arguments and invoke that command. Caveat:

• Changing the persistent current-user configuration also takes effect for regular PowerShell sessions (interactive ones / CLI calls) in the respective PowerShell edition.

• By contrast, if you change the persistent machine configuration - which requires running with elevation (as admin):

  • With the Windows PowerShell SDK, the change also takes effect for regular PowerShell sessions.
  • With the PowerShell (Core) SDK, it only takes effect for the SDK project at hand.^[1]

• See this answer for sample code.

Caveat:

• If the current user's / machine's execution policy is controlled via GPOs (Group Policy Objects), you fundamentally cannot override it programmatically (except via GPO changes).

• To check if a GPO-based policy is in effect:

  • Run Get-ExecutionPolicy -List to list policies defined for each available scope, in descending order of precedence.
  • If either the MachinePolicy or the UserPolicy scope have a value other than Undefined, then a GPO policy is in effect (run Get-ExecutionPolicy without arguments to see the effective policy for the current session).

---

Limited workaround for when a GPO-based policy prevents script-file execution:

Assuming all of the following; script file refers to *.ps1 files:

• Your script file calls no other script files.
• It (directly or indirectly) loads no modules that on import happen to call script files.
• Your script file doesn't rely on knowing its own location (directory) or name on disk.

You can load your script file's content into a string and pass that string to the SDK's .AddScript() method, as the following simplified example shows:

using (var ps = PowerShell.Create()) {

  var results =
    ps.AddScript(File.ReadAllText(path + "\\" + fileName))
      .AddParameters(commandParameters)
      .Invoke();

}

---

^{[1] Windows PowerShell stores the execution policies in the registry, which both regular sessions and the SDK consult. By contrast, PowerShell (Core) stores them in powershell.config.json files, and in the case of the machine policy alongside the PowerShell executable (DLL). Since SDK projects have their own executable, its attendant JSON file is not seen by the executable of a regular PowerShell (Core) installation.}