Update: When you’re done here, read Part II.

Although we’ve discussed the $PSDefaultParameterValues before, I wanted to do a quick recap. I need one place that shows the various ways to set this variable. That’s what this post will do for me, and perhaps you too.

First, however, let’s remind everyone what the $PSDefaultParameterValues variable does for us. It allows us to set a custom, default value for a function or cmdlet’s parameter. One of the examples I mentioned before, in one of the three posts I’ve written about $PSDefaultParameterValues (1 | 2 | 3), used Get-Help.

This cmdlet includes a ShowWindow switch parameter that will open the full help inside its own GUI window. I tend to use this option a great deal to keep my ConsoleHost clean. In order to keep this post short, I’m just going to write the three ways in which I’m aware that we can set this variable.

$PSDefaultParameterValues.Add('Get-Help:ShowWindow',$true)

$PSDefaultParameterValues = @{'Get-Help:ShowWindow' = $true}

$PSDefaultParameterValues['Get-Help:ShowWindow'] = $true

Oh, Lee Holmes posted a welcome PSDefaultParameterValues addition on Twitter recently. I’ve included that addition below using the three above options, as well. Unlike his example, I moved from three underscores to two. You’ll see what I mean below if you haven’t already read the Tweet.

With this example in place, the results of all the commands entered will end up in the $__ variable. Again, that’s two underscores. Run a Get-ADUser command, for instance, and you’ll get the results both on the screen and in the $__ variable up until you run another command that can make use of the OutVariable common parameter.

$PSDefaultParameterValues.Add('Out-Default:OutVariable','__')

$PSDefaultParameterValues = @{'Out-Default:OutVariable' = '__'}

$PSDefaultParameterValues['Out-Default:OutVariable'] = '__'