Custom error messages in PowerShell - Mini Project: Build & Apply

Custom error messages

📖 Scenario: You are writing a PowerShell script to check if a file exists before processing it. If the file does not exist, you want to show a clear, custom error message to help users understand what went wrong.

🎯 Goal: Build a PowerShell script that checks for a file's existence and shows a custom error message if the file is missing.

📋 What You'll Learn

Create a variable holding the file path

Create a variable holding a custom error message

Use an if statement to check if the file exists

Show the custom error message if the file does not exist

Print a success message if the file exists

💡 Why This Matters

🌍 Real World

Scripts often need to check if files or resources exist before working with them. Clear error messages help users fix problems quickly.

💼 Career

Knowing how to handle errors and show helpful messages is important for system administrators and automation engineers to create reliable scripts.

1

Set the file path variable

Create a variable called $filePath and set it to the string "C:\temp\data.txt".

PowerShell

# Create the file path variable
# Your code here

Need a hint?

Use = to assign the string to the variable $filePath.

2

Create the custom error message variable

Create a variable called $errorMessage and set it to the string "Error: The file does not exist at the specified path.".

PowerShell

$filePath = "C:\temp\data.txt"
# Create the custom error message variable
# Your code here

Need a hint?

Assign the error message string to $errorMessage using =.

3

Check if the file exists

Write an if statement that uses Test-Path with $filePath to check if the file exists. Inside the if, write a Write-Host command to print "File found.". In the else block, write a Write-Host command to print the $errorMessage variable.

PowerShell

$filePath = "C:\temp\data.txt"
$errorMessage = "Error: The file does not exist at the specified path."

# Write an if statement to check if the file exists
# Use Write-Host to print messages
# Your code here

Need a hint?

Use Test-Path $filePath inside the if condition. Use Write-Host to print messages.

4

Display the result

Run the script to display either File found. if the file exists or the custom error message if it does not.

PowerShell

$filePath = "C:\temp\data.txt"
$errorMessage = "Error: The file does not exist at the specified path."

if (Test-Path $filePath) {
    Write-Host "File found."
} else {
    Write-Host $errorMessage
}

# Run the script to see the output
# Your code here

Need a hint?

Run the script in PowerShell. It will print one of the two messages depending on the file's existence.