Why does everyone say that "Add-PSSnapin VMware.VimAutomation.Core" is necessary?

[maikeru1028]

Every thread I read says you need to put "Add-PSSnapin VMware.VimAutomation.Core" at the top of any script or commands if you want to run them from PowerShell (and not PowerCLI).

However, when I add that to my script, PowerShell (2.0) will continue on and run the script, but it will throw me a nice big red warning (I guess it's not an error because the script ultimately runs), saying that "VMware.VimAutomation.Core" is already included and thus can't be added again.

I never did anything to configure or change PowerShell, ever.  In fact, this is only like day 2 of using PowerShell.  So it's in its straight-out-of-the-box condition.  Yet every forum I go to just goes on and on about how this is necessary and stuff.  Just wondering, what gives?  What's the story/explanation here?  Do I just have some kind of freak mutant version of PowerShell?    

[sflanders · Accepted solution]

Adding it just ensures it is loaded in case it is not. Certain applications (e.g. PowerGUI) allow you to load the snap-ins by default removing the need for adding it to every script. If you do not add it to your scripts and it is not loaded and you attempt to run PowerCLI commands the operations will fail as the commands will not be know. People typically consider it a best practive to include the snap-in at the beginning of scripts so it is easier to transport.

[Dave_Mishchenko]

Perhaps its been added to your PS profile - C:\Documents and Settings\\Documents\ WindowsPowerShell\Microsoft.PowerShell_profile.ps1.

[RvdNieuwendijk]

To prevent the Add-PSSnapin cmdlet to throw a warning message you can add "2> $null" to the line. This writes the message to the null device. Which is the same as throwing it away. So:

Add-PSSnapin VMware.VimAutomation.Core 2> $null

[LucD]

It's probably already added in one of your profiles.

You can add it conditionally like this

if(!(Get-PSSnapin | where {$_.Name -eq "VMware.VimAutomation.Core"})){
    Add-PSSnapin "VMware.VimAutomation.Core"}

[avlieshout]

Nice one Luc.

Never thought of adding it conditionally.