Powershell - Check if specific modules are installed and take action if not installed-CodePudding

new to stackoverflow and novice at Powershell, so go easy.

I'm looking for a way for a Powershell script to check if specific modules are installed. If not then give a message asking if they would like to install those not installed. If all are installed then proceed with the script.

I've seen the '#requires -Module' option but I want to provide a better prompt rather than the Powershell red text.

For reference, I want to check if AzureAD, ExchangeOnlineManagement, and MSOnline modules are installed

Any help appreciated.

Regards, Lee

CodePudding user response：

To offer an alternative to Steven's helpful answer that handles the missing modules as a group :

# Define all required modules
$modules = 'AzureAD', 'ExchangeOnlineManagement', 'MSOnline'

# Find those that are already installed.
$installed = @((Get-Module $modules -ListAvailable).Name | Select-Object -Unique)

# Infer which ones *aren't* installed.
$notInstalled = Compare-Object $modules $installed -PassThru

if ($notInstalled) { # At least one module is missing.

  # Prompt for installing the missing ones.
  $promptText = @"
  The following modules aren't currently installed:
  
      $notInstalled
  
  Would you like to install them now?
"@
  $choice = $host.UI.PromptForChoice('Missing modules', $promptText, ('&Yes', '&No'), 0)
  
  if ($choice -ne 0) { Write-Warning 'Aborted.'; exit 1 }
  
  # Install the missing modules now.
  # Install-Module -Scope CurrentUser $notInstalled
}

CodePudding user response：

As alluded to in your question, there are a few ways to ensure modules are available to a script or module. Modules can define other modules as well as other prerequisites. #Requires can be used, but neither facility will prompt or otherwise install a module. Instead, they will prevent the loading or running of the dependent script etc.

If you want to start building a function you can check if a module is available on the given system with:

Get-Module -Name <ModuleName> -ListAvailable

You can wrap this in a loop with an If block to cover multiple modules:

ForEach( $Module in $RequiredModules ) 
{
    If ( !(Get-Module -ListAvailable -Name $Module) ) {
        # find, install and load the module.
    }
}

I would draw your attention to the other *Module cmdlets to build out the remaining functionality you described.