Determine if Powershell script started in main scope?

Question

I am a beginner Powershell user. I am writing some script files (.ps1)

I would like to determine how my script was invoked:

Was is the "main" script or was it dot sourced from another file?

In python, I would use something like:

if __name__ == "__main__":

Is there something similar in PowerShell?

Update

After reading the answers, I am using the following at the end of my .ps1 file:

if ($MyInvocation.InvocationName -ne '.')
{
  # do "main" stuff here
}

Any answers that include how this could fail are welcome.

It appears this is a duplicate question, I just didn't use the right search terms: Determine if PowerShell script has been dot-sourced

@HyperAnthony thanks for the link. Is there a equivalent one-liner for PowerShell to the python version? I understand that PowerShell scripts are ran from top to bottom. So I'd like to put a test condition near the bottom of my script that only if it passes, does the remainder of the script run. — Josh Petitt
– Josh Petitt, Commented Mar 10, 2014 at 20:19

mjolinor · Accepted Answer · 2014-03-10 20:32:30Z

5

If you're wanting to know how it was invoked, have a look at the $myinvocation automatic variable.

If you just want to test if you're in the global scope:

Try {if (get-variable args -scope 1){$true}}
Catch {$false}

should return $true if you're running in a child scope. If you're already in the global scope, there is no parent scope and it will throw an error and return $false.

answered Mar 10, 2014 at 20:32

mjolinor

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4 Comments

Josh Petitt Over a year ago

thank you, this seems to be good information. Do you know if the $myinvocation.CommandOrigin would give me what I want? My preliminary testing seems to show 'Runspace' if I started the script from powershell, and 'Internal' if another script is calling it? I have not found any detailed info on the CommandOrigin member.

Josh Petitt Over a year ago

I also see the InvocationName which seems to be either a '.' or the name of the script? Maybe this is a better way?

mjolinor Over a year ago

I don't know Python, so I'm not quite sure what to tell you to look for that would be the analog of that Python command.

mjolinor Over a year ago

Thanks! Every scope gets initialized with it's own $args, so it should always be there :).

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