PowerShell: Load WebAdministration in ps1 script on both IIS 7 and IIS 7.5

iispowershell

I have a PowerShell script that configures web site and web application settings in IIS. So I use the cmdlets in the WebAdministration snap in. But this script needs to run on Windows 2008, Windows 7 and Windows 2008 R2. And I need it to run with minimal fuss from the user.

The problem is that Windows 7 and Windows 2008 R2 use IIS 7.5 which comes with the WebAdministration installed as a module. On Windows 2008 we have installed the IIS 7 PowerShell provider which installs WebAdministration as a snap in.

So including import-module WebAdministration in the script blows up on IIS 7 but works fine on IIS 7.5 and including add-pssnapin WebAdministration blows up on IIS 7.5 but works fine on IIS 7.

So our workaround is to make the administrators load WebAdministration manually with the appropriate command for the environment before running the script. But this isn't optimal as it is easy to forget which command works in which environment. We could create two different scripts, but that creates a maintenance problem for development.

Has anyone solved this problem? Does anyone know how to check the environment and then call the appropriate cmdlet from within the PS script?

— ANSWER (for my situation) —-

The solution is a combination of code and pre-configured console. The IIS 7 PoSH Provider includes a desktop shortcut that launches a PoSH console with WebAdministration loaded. That combined with the following function make my script run like a charm on all three systems.

Function Load-WebAdmin {
  $webAdminModule = get-module -ListAvailable 
                                        | ? { $_.Name -eq "webadministration" }
  If ($webAdminModule -ne $null) {
    import-module WebAdministration
  }
}

Best Answer

This is probably a bit late to help you, but here is how we do this:

$iisVersion = Get-ItemProperty "HKLM:\software\microsoft\InetStp";
if ($iisVersion.MajorVersion -eq 7)
{
    if ($iisVersion.MinorVersion -ge 5)
    {
        Import-Module WebAdministration;
    }           
    else
    {
        if (-not (Get-PSSnapIn | Where {$_.Name -eq "WebAdministration";})) {
            Add-PSSnapIn WebAdministration;
        }
    }
}

Exit vs Return vs Break

Exit: This will "exit" the currently running context. If you call this command from a script it will exit the script. If you call this command from the shell it will exit the shell.

If a function calls the Exit command it will exit what ever context it is running in. So if that function is only called from within a running script it will exit that script. However, if your script merely declares the function so that it can be used from the current shell and you run that function from the shell, it will exit the shell because the shell is the context in which the function contianing the Exit command is running.

Note: By default if you right click on a script to run it in PowerShell, once the script is done running, PowerShell will close automatically. This has nothing to do with the Exit command or anything else in your script. It is just a default PowerShell behavior for scripts being ran using this specific method of running a script. The same is true for batch files and the Command Line window.
Return: This will return to the previous call point. If you call this command from a script (outside any functions) it will return to the shell. If you call this command from the shell it will return to the shell (which is the previous call point for a single command ran from the shell). If you call this command from a function it will return to where ever the function was called from.

Execution of any commands after the call point that it is returned to will continue from that point. If a script is called from the shell and it contains the Return command outside any functions then when it returns to the shell there are no more commands to run thus making a Return used in this way essentially the same as Exit.
Break: This will break out of loops and switch cases. If you call this command while not in a loop or switch case it will break out of the script. If you call Break inside a loop that is nested inside a loop it will only break out of the loop it was called in.

There is also an interesting feature of Break where you can prefix a loop with a label and then you can break out of that labeled loop even if the Break command is called within several nested groups within that labeled loop.
```
While ($true) {
    # Code here will run

    :myLabel While ($true) {
        # Code here will run

        While ($true) {
            # Code here will run

            While ($true) {
                # Code here will run
                Break myLabel
                # Code here will not run
            }

            # Code here will not run
        }

        # Code here will not run
    }

    # Code here will run
}
```

Best Answer

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Exit vs Return vs Break

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