Hey, Scripting Guy! I have been reading your articles about working with Windows PowerShell profiles, and they are pretty cool. However, I have a question. You mentioned on Monday that I could add a function to a Windows PowerShell profile. I am not sure how I would do that. Can you add a function to the profile you have been working on all week to give me a better idea?

— AM

Hello AM,

Microsoft Scripting Guy Ed Wilson here. As the hour hand creeps closer to the top of the clock and the evening chill fills the air, my taste in music changes. I am listening to Charlie Daniels on my Zune HD and sipping a cup of Constant Comment tea, and munching on a slice of a Virginia mountain apple that the Scripting Wife picked up on her recent trip to Kentucky. A chunk of artisan cheese rounds out the late-night snack.

AM, in addition to writing the Hey Scripting Guy! column, one of my favorite things in life is writing Windows PowerShell scripts. I know you asked specifically about adding a function to your profile, and here I am talking about writing Windows PowerShell scripts. This is because a Windows PowerShell profile is basically a script. As I mentioned in Monday’s Hey Scripting Guy! post, it is somewhat akin to the old fashioned AUTOEXEC.BAT file that you may have messed around with 20 years ago. It has a special name, and it is located in a special location. Other than that, it is a plain old everyday Windows PowerShell script.

A more confusing line in Windows PowerShell 2.0 blurs between functions/advanced functions and Windows PowerShell scripts. Functions, and in particular advanced functions, have the same elements that a Windows PowerShell script possesses. A function can accept parameters, produce Help, and…but wait, we will be talking about Windows PowerShell functions in a couple weeks (the week of December 21, 2009). We’ll save that discussion for then.

Note: Portions of today’s Hey Scripting Guy! post are excerpted from the Microsoft Press book, Windows PowerShell 2.0 Best Practices by Ed Wilson. The book is available for pre-order.

The easiest way to explain adding a function to the Windows PowerShell profile is to go ahead and add one to it.

This assumes you have created a Windows PowerShell profile. If you have not, refer back to Monday’s Hey, Scripting Guy! post.

Open your profile in Notepad. You can do this from inside the Windows PowerShell console by typing Notepad followed by the $profile automatic variable. This is seen here:

Notepad $profile

The Windows PowerShell profile we have been working on all week is displayed. It is seen in the following image:

On Monday when we were creating our Windows PowerShell profile, we added comments to create sections of the profile for each of the four things commonly placed in a profile. We now want to add a function, which goes in the (wait for it) function section. One function you will want to add to your Windows PowerShell profile is one that opens your profile in Notepad so that you can edit it. To do this, use the Function keyword to tell Windows PowerShell you are creating a function, and then give the function a name. As a best practice when writing Windows PowerShell scripts, you should always use a two-part name that comprises a verb and a noun. For ideas of good verbs to use, you can use the Get-Verb function to provide a list of approved verbs:

Because the Get-Profile function will open the profile in Notepad, it “gets” the profile. This is why I named the function Get-Profile. The command you wish to execute is placed between the two curly brackets. As a Windows PowerShell best practice, you should add a comment to your closing curly brackets that indicates what the closing bracket is doing. This will greatly facilitate troubleshooting your scripts.

I learned this best practice when I was taking the ICE train from Regensburg to Hamburg in Germany a few years ago. It is a five-hour trip, and shortly after the train departed the HBF in Regensburg, I introduced an error into the script I was writing. I did not find the error until the train crossed the final bridge before entering the Hamburg HBF. The problem, of course, was a missing curly bracket. As a direct result of that experience, I began adding closing comments to my curly brackets.

The Get-Profile function is seen here:

Function Get-Profile
{
 Notepad $profile
} #end function get-profile

The other thing I like to do is to create an alias for a function that I add to my Windows PowerShell profile. The reason I am adding the function to the profile in the first place is because I anticipate I will be using it on a regular basis. If I am going to be using the function on a regular basis, it makes sense to create a alias for it.

Before creating a new alias, it is a best practice to see if there is a suitable alias already created for the cmdlet in question. By default, Windows PowerShell ships with more than 130 predefined aliases for its 271 cmdlets, and many of them are two-letter aliases. The two-letter aliases are shown here:

PS C:> Get-Alias ??

You do not want to go to all the trouble of editing your profile, and restarting Windows PowerShell only to find out there is a conflict with your alias choice. My first choice for an alias for the Get-Profile function would be gp. To see if it is available, use the Get-Alias cmdlet as seen here:

PS C:> Get-Alias gp

As you can see, the alias gp is already taken unfortunately. We have two options, remove the gp alias by using the Remove-Item cmdlet, or choose something else. To remove the gp alias, you will need to use the Force parameter. This is because it is a read-only alias. This is seen here:

PS C:> Remove-Item alias:gp
Remove-Item : Alias was not removed because alias gp is constant or read-only.
At line:1 char:12
+ Remove-Item <<<<  alias:gp
    + CategoryInfo          : WriteError: (gp:String) [Remove-Item], SessionStateUnauthorizedAccessException
    + FullyQualifiedErrorId : AliasNotRemovable,Microsoft.PowerShell.Commands.RemoveItemCommand

In the end, I decided to use p as the alias for the