How To Create a Powershell Script SCCM Detection Method

Introduction

This blog post explains how you can use a Powershell script in an SCCM detection method to detect file content.

My detection method scenario

I came across a customer scenario where configuration files were replaced in the installation directory during application installation using a script. Since a configuration line was different in the different files, this had to be checked during the application detection after the installation.

The easy way out would have been to detect the configuration file’s existence, but I also wanted to make sure the file’s content was correct.

How to use SCCM detection methods

When configuring SCCM detection methods, you want the Detection Method to be as granular as possible.

Some out-of-the-box Detection Methods which work very well:

• MSI
• Registry keys
• File version

Detection Methods are one of the main culprits when dealing with application deployment issues.

Sometimes the Detection Method is misconfigured, and the SCCM client does not detect the application as installed, or a Detection Method is configured as non-granular.

An example of this is adding to a script that a text file is to be created and then use it to detect if the application is installed. This is not the right way to configure detection methods in SCCM.

Read more about Powershell Detection Methods here: Microsoft Docs – Introduction to Application Management.

Powershell script detection methods in SCCM

How Powershell script detection methods work

When creating Powershell detection methods in SCCM, you need to understand how they work. Understanding how the Powershell detection method works include understanding how SCCM interprets your Powershell detection method’s output.

The below table from Microsoft Docs shows how the script output defines the result:

My Powershell SCCM detection method solution

Introduction

This solution uses Powershell to parse a text file, which in my example is a configuration file. The Powershell script returns a result upon string discovery.

You can use this solution as an example if you want to look for other strings in text files.

How to implement the Powershell detection method solution

Step 1 – Create the application

Start by going to the Software Library and press Create Application.

Select Manually specify the application information.

Enter the information about the application.

Input any additional information about the application.

Step 2 – Create the deployment type

On the next step, press Add to add a new Deployment Type.

Select Manually specify the deployment type information.

Enter the Name of the Deployment Type. The Deployment Type name can be anything.

Enter the installation instructions of the application according to your requirements.

Step 3 – Create the Powershell detection method

Now we are the main subject of this blog post, namely SCCM detection methods using a Powershell script.

Select Use a custom script to detect the presence of the deployment type. Press Edit.

Modify the Powershell script

Modify the below script to suit your needs. The example below will look at strings in 3 different files. You will need to make the following modifications:

• String variables
• String<number>Location variables

Change Script type to Powershell and enter the code below this screenshot in the text box. You will, of course, need to modify it to suit your needs.

Powershell detection method example

#Define strings and their location. Also include the filename.
$String1 = ""
$String1Location = ""
$String2 = ""
$String2Location = ""
$String3 = ""
$String3Location = ""
# Detect presence of String1 in String1 Location
try {
    $String1Exists = Get-Content $String1Location -ErrorAction Stop
}
catch {
}
# Detect presence of String2 in String2 Location
try {
    $String2Exists = Get-Content $String2Location -ErrorAction Stop
}
catch {
}
# Detect presence of String3 in String3 Location
try {
    $String3Exists = Get-Content $String3Location -ErrorAction Stop
}
catch {
}
if (($String1Exists -match $String1) -and ($String2Exists -match $String2) -and ($String3Exists -match $String3)) {
    Write-Host "Installed"
}
else {
}

Step 4 – Finalize the application

Once you have added the Detection Method, you will need to go through the rest of the wizard to finalize the process.

Step 5 – Distribute and deploy the application

End by Distributing and Deploying the application to users or devices, depending on your environment.

Conclusion

Powershell Detection Methods are powerful to use when you cannot use the default MSI, registry, or file version detections. However, they are a bit more complicated and getting your head around how the script work’s return logic might take some time.

For all scenarios, when you can use a built-in Detection Method, use that, but in all other custom cases, you can use Powershell Detection Methods.

References

• Microsoft Docs – Introduction to Application Management
• Microsoft Docs – How to create Applications in Configuration Manager

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