Understand and Use Test-FileCatalog in PowerShell

Welcome back to Wahman’s PowerShell Blog! Today we’re diving into a lesser-known, but very useful cmdlet in Windows PowerShell: Test-FileCatalog.

Test-FileCatalog helps validate file catalogs (.cat) by checking if the hashes within the catalog match the current state of the files listed. This is particularly valuable for verifying file authenticity and ensuring integrity, which is critical in secure scripting and system deployments.

It’s important to note: this cmdlet only works on Windows.

Why Use Test-FileCatalog?

• To verify files haven’t been tampered with after deployment.
• To ensure software is authentic and unmodified (e.g., driver packages or signed installation packages).
• To comply with internal or external security policies requiring integrity checks.

Let’s explore 4 use cases – from beginner to advanced!

1. Basic Catalog Verification

Let’s start with the simplest case: you have a catalog file and want to verify it against its associated files.

Test-FileCatalog -Path "C:\MyFiles\filecatalog.cat"

This will output True if everything checks out or False if any file hash doesn’t match the catalog.

2. Verbose Output for Troubleshooting

PowerShell supports detailed output using -Verbose for insight into what’s happening under the hood.

Test-FileCatalog -Path "C:\MyFiles\filecatalog.cat" -Verbose

This shows which file failed validation, making debugging easier.

3. Validating Multiple Catalogs in a Directory

Let’s say you have multiple catalogs in a folder and want to validate all of them.

Get-ChildItem -Path "C:\Catalogs" -Filter "*.cat" | ForEach-Object {
    $result = Test-FileCatalog -Path $_.FullName
    Write-Host "Catalog: $($_.Name) - Valid: $result"
}

Each catalog is tested, and you get a summary of their validity.

4. Advanced: Validate Catalog and Act on Failure

Let’s say you’re deploying an app and you require the catalog to pass validation before proceeding.

$catalogPath = "C:\Apps\Package1\app.cat"

if (Test-FileCatalog -Path $catalogPath) {
    Write-Host "Catalog is valid. Proceeding with deployment..."
    # Add deployment logic here
} else {
    Write-Error "Catalog validation failed. Aborting deployment!"
    # Optionally: Log this to an audit trail
}

This introduces logic control into your scripts based on file integrity.

Wrap Up

Test-FileCatalog is a powerful cmdlet to ensure you’re working with untampered, authenticated files. From simple validations to integrating it into deployment logic, it provides peace of mind when dealing with sensitive or critical data.

Until next time…

Happy scripting, and I will see you in the next post!