Checking Cmdlet Availability and Script Compatibility (Part 2)

Not all PowerShell cmdlets ship with PowerShell. Many are part of 3rd party modules which in turn ship when you install certain software, or use certain Windows versions.

In the previous part we worked on a script that dumps all the external commands used by a script. We consolidated the findings with this function:

function Get-ExternalCommand
{
    param
    (
        [Parameter(Mandatory)][string]
        $Path
    )
    function Get-ContainedCommand
    {
        param
        (
            [Parameter(Mandatory)][string]
            $Path,

            [string][ValidateSet('FunctionDefinition','Command')]
            $ItemType
        )

        $Token = $Err = $null
        $ast = [Management.Automation.Language.Parser]::ParseFile($Path, [ref] $Token, [ref] $Err)

        $ast.FindAll({ $args[0].GetType().Name -eq "${ItemType}Ast" }, $true)

    }


$functionNames = Get-ContainedCommand $Path -ItemType FunctionDefinition | 
   Select-Object -ExpandProperty Name
   
    $commands = Get-ContainedCommand $Path -ItemType Command 
    $commands | Where-Object {
      $commandName = $_.CommandElements[0].Extent.Text
      $commandName -notin $functionNames
      } | 
      ForEach-Object { $_.GetCommandName() } |
      Sort-Object -Unique
} 

You can submit any PowerShell script path to this function and receive all external commands used by that script (just make sure you submit a valid path to a script file in $path):

 
PS C:> Get-ExternalCommand -Path $Path
ConvertFrom-StringData
Get-Acl
Get-ItemProperty
Get-Service
Get-WmiObject
New-Object
out-default
Test-Path
Where-Object
write-host
 

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