How to find cmdlet in the entire folder

By Robert Dyjas on  • Edit this post

Learn how to find certain PowerShell cmdlets in all the scripts in the folder.

In this article we'll build a script. It will search for a cmdlet inside our script folder.

This blog post was inspired by the Microsoft Message Center announcement MC316139. It says about changes in the number assignment process via PowerShell.

The announcement points out three cmdlets to be fully retired. It also mentioned one cmdlet to be deprecated only for number assignment functionality.

Issue

After we read the announcement, one question popped up. How to verify if the change affects our scripts? Let's try to go step by step and find a way.

How to find where we use the cmdlets?

We'll follow a few steps:

  • Define the list of cmdlets
  • Get all .ps1 files in the folder and its subfolders
  • Search the files for any of the cmdlets

Defining the list of cmdlets

We'll need an array of the string objects. Each element of the array will be a single cmdlet.

There are several ways to define such an array. We can do it in one line:

$cmdletsToBeChecked = @("Set-CsUser", "Set-CsOnlineVoiceUser", "Set-CsOnlineApplicationInstance", "Set-CsOnlineVoiceApplicationInstance")

I prefer a way where I can easily paste the list. Each element comes to a separate line.

We can achieve this using here-string.

Let's convert it to an array using -split operator. Our delimiter will be a newline character.

$cmdletsToBeChecked = @"
Set-CsUser
Set-CsOnlineVoiceUser
Set-CsOnlineApplicationInstance
Set-CsOnlineVoiceApplicationInstance
"@ -split "`n"

# A quick test to verify
$cmdletsToBeChecked[0]
# Should return
# Set-CsUser

Tip

Depending on the OS, you might experience different splitting behavior. Check this StackOverflow topic to find more options.

Getting all script files

Now let's find all script files. We'll search the selected folder and its subfolders.

The cmdlet we use is Get-ChildItem.

We'll make use of some parameters:

  • File to not output folders
  • Recurse to go down the entire folder tree
  • Filter to get only .ps1 files
# Save folder path to a variable
$scriptFolderPath = 'C:\temp'

# Iterate through the folder
Get-ChildItem -LiteralPath $scriptFolderPath -File -Recurse -Filter "*.ps1"

Searching the files

Last, but not least - let's search the files. We'll use Select-String cmdlet.

We pipe the folder from the previous step. Select-String will check all of them. The cmdlet will search for a pattern we provide via the Pattern parameter.

The pattern value is treated as a regular expression. We're not going to dig into regex in this article. If you want to expand your knowledge on that topic, check about_Regular_Expressions.

For the purpose of this exercise we need to know the regex alternation. We'll separate the cmdlets with |. We'll get a match if any of them is found.

We have the cmdlets already saved to a variable. We need to convert them to a string separated with regex alternation. Luckily we have a -join operator:

<# Result from previous step #> | Select-String -Pattern ($cmdletsToBeChecked -join "|")

Full script

Ok, we know all the steps. Let's compile them together:

$scriptFolderPath = 'C:\temp'
$cmdletsToBeChecked = @"
Set-CsUser
Set-CsOnlineVoiceUser
Set-CsOnlineApplicationInstance
Set-CsOnlineVoiceApplicationInstance
"@ -split "`n"

# Line break added for visibility
Get-ChildItem $scriptFolderPath -File -Recurse -Filter "*.ps1" | 
  Select-String -Pattern ($cmdletsToBeChecked -join "|")

Limitations

There are some edge cases for this script. It won't work unless we're using the full name of the cmdlet.

Example of what won't be detected:

$verb = 'Get'
$noun = 'CsUser'
 & "$verb-$noun"

Conclusion

When we learn that a cmdlet (or four of them) is being retired, we need to take care of it. Proper discovery is crucial - we need to know what to replace.

In this article, we've built a script to do proper discovery. We learned about useful cmdlets, splitting an array, and using regular expressions.

Now we're ready to run the script and do our discovery!