Powershell – In PowerShell, how to define a function in a file and call it from the PowerShell commandline


I have a .ps1 file in which I want to define custom functions.

Imagine the file is called MyFunctions.ps1, and the content is as follows:

Write-Host "Installing functions"
function A1
    Write-Host "A1 is running!"
Write-Host "Done"

To run this script and theoretically register the A1 function, I navigate to the folder in which the .ps1 file resides and run the file:


This outputs:

Installing functions

Yet, when I try to call A1, I simply get the error stating that there is no command/function by that name:

The term 'A1' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling
 of the name, or if a path was included, verify that the path is correct and try again.
At line:1 char:3
+ A1 <<<<
    + CategoryInfo          : ObjectNotFound: (A1:String) [], CommandNotFoundException
    + FullyQualifiedErrorId : CommandNotFoundException

I must misunderstand some PowerShell concepts. Can I not define functions in script files?

Note that I have already set my execution policy to 'RemoteSigned'. And I know to run .ps1 files using a dot in front of the file name: .\myFile.ps1

Best Solution

Try this on the PowerShell command line:

. .\MyFunctions.ps1

The dot operator is used for script include, aka "dot-sourcing" (or "dot source notation")

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