How to determine "stranger" argument, passed to PS script

PowerShell Help
1

Hi big and all-knowing ALL.
I have PS script that uses named parameters. Something like:

param (
    [switch]$help
 )
function Usage
{
    write-host "Usage:"
    exit 1
}
if ($help){ Usage }

If I invoke it like:
myScript.ps1 --help

everything works fine - I get usage.
If I invoke it without parameters - it also is Ok - I get nothing.
Problem occurs when I invoke it with total wrong parameter. For example :

myScript.ps1 --kuku
or
myScript.ps1 kuku

In this case “param” section simply ignore parameter, that does not suit its definitions.
Of cause I can abandon “param” section and switch to primitive loop over @args array and manual parsing of arguments. This way I can for sure discover that user entered unsupported argument.
But question is - do PS have more elegant way to do such validation?
I believe - it have to have something that do it, since problem seems to be fairly common. But I can not find anything that suite this task… :anguished:

2

Try adding:

[CmdletBinding()]

At the beginning of your script.

1 Like
3

Hi, welcome to the forum :wave:

As well as [CmdletBinding()], for the specific purpose of providing help information, look into about Comment Based Help - PowerShell | Microsoft Docs

This will allow you to take full advantage of the PowerShell help system which, for very little extra effort, gives you a lot of nice features.

1 Like
4

10x - will try it.
Looks promising

5

Hi Tony
I have used [CmdletBinding()] and it generally do what I need.
But I face 2 problems - that I do not success to solve.

  1. If I pass wrong parameter - PS throws error message about it (as expected ) and stops execution of script. Good! But I did not success to find a way to customize this error message. Is it possible?

  2. In case of wrong parameter - exit code of script is - 0. Can I change it somehow to be for example - 1? So - caller script/batch will “know” that something gone wrong?

6

Do some one have any idea about how to customize CmdletBinding error message about wrong parameter, and exit code that is thrown from script?

7

I would encourage you to investigate the link on Comment Based Help posted by matt-bloomfield. There really is no reason to write code for help when that functionality is built into PowerShell.

8

Hi Darwin. Generally I agree with you.
But I have pre-defined requirement, that in case of wrong command-line parameters script will exit with exit code 1.
And default behavior, pre-scribed by use of CmdletBinding - exit code is - 0.
Although - you get err-message about wrong parameter, but exit code of script is - 0

9

You’re calling the ps1 file? Please show us exactly how you’re invoking, formatted as code please

10

Hi krzydoug

powershell.exe -ExecutionPolicy Bypass -File check_java_ready.ps1 -java_path c:\kuku_java

11

In this case your powershell.exe command completes successfully, so the exit code would be 0. If it has an error itself it will return an error. I remember reading something about this but can’t find it at the moment. In the meantime, I’d check $lastexitcode it code in your script itself.

12

Check Michael’s answer here Returning an exit code from a PowerShell script - Stack Overflow