Parameters to a function of a module in Powershell

Question

I was able to execute this command before trying to make a function out of it..

$unzip ="c:\path\To\myZip.zip"
$dst = "c:\destination"
saps "c:\Program Files\winzip\wzunzip.exe" "-d $unzip $dst" -WindowStyle Hidden -Wait

Then I created this function in a module that I am trying to pass parameters to..

function RunCmd ($cmd){
    write-host "cmd: $cmd" 
    saps $cmd -WindowStyle Hidden -Wait 
}

I have verified that the module has been imported correctly, but when I try and pass the parameters to the function I get errors stating that the argument cannot be read.

I've tried multiple ways to pass the parameters, but nothing works.

Examples

$cmd = @{'FilePath'= '$unzip';
     'ArgumentList'= '-d $unzip dst';}
RunCmd  @cmd


RunCmd """$unzip"" ""-d $unzip $dst"""

I have noticed that the command and arguments will be passed to the function in double quotes doing the second alternative, but that's when I get the arguments null exception.

I have also tried to change the function to pass the command and arguments separately without success..

function RunCmd ($cmd, $args){
    write-host "cmd: $cmd" 
    saps $cmd $args -WindowStyle Hidden -Wait 
}

Any ideas?

UPDATE:

this is my new function..

function RunCmd ($log, $cmd, $args){
    Log-Cmd $log
    saps -FilePath $cmd -ArgumentList $args -WindowStyle Hidden -Wait 
}

have also tried..

> function RunCmd ($log, $cmd, [string[]]$args){
>     Log-Cmd $log
>     saps -FilePath $cmd -ArgumentList $args -WindowStyle Hidden -Wait  }

but when the function tries to execute I get an error saying that the arguments are null.

Start-Process : Cannot validate argument on parameter 'ArgumentList'. The argument is null, empty, or an element of the argument collection contains a null value. Supply a collection that does not contain any null values and then try the command again. At c:\path\to\module\myModule.psm1:39 char:38 + saps -FilePath $cmd -ArgumentList <<<< $args -WindowStyle Hidden -Wait + CategoryInfo : InvalidData: (:) [Start-Process], ParameterBindingValidationException + FullyQualifiedErrorId : ParameterArgumentValidationError,Microsoft.PowerShell.Commands.StartProcessCommand

I have tried multiple ways to call this function..

RunCmd -log $log -cmd $unzip -args '-d', '$unzip', '$dst'
RunCmd $log $unzip '-d', '$unzip', '$dst'
RunCmd $log $unzip "-d", "$unzip", "$dst"

Show exact invocations and exact errors from the various attempts. — Etan Reisner

beatcracker beatcracker · Accepted Answer · 2015-09-09T02:12:26

You have to pass arguments to the Start-Process cmdlet as array of strings. Here is the very basic example:

function Unzip-File ($ZipFile, $Destination)
{
    $wzunzip = 'c:\Program Files\winzip\wzunzip.exe'
    Start-Process -WindowStyle Hidden -Wait -FilePath $wzunzip -ArgumentList (
        '-d',
        $ZipFile,
        $Destination
    ) 
}

Unzip-File 'c:\path\To\myZip.zip' 'c:\destination'

Update:

is there a way to pass the exe file to the function as well? I'll eventually have multiple exe files coming into the function that logs the command and then executes it.

Sure:

function Start-ProcAndLog ($ExeFile, $CmdLine)
{
    Start-Process -WindowStyle Hidden -Wait -FilePath $ExeFile -ArgumentList $CmdLine
}

# Note commas in second parameter: '-arg1', '-arg2', '-arg3' is an array
Start-ProcAndLog 'c:\path\to\file.exe' '-arg1', '-arg2', '-arg3'

Parameters to a function of a module in Powershell

1 Answers

Update: