Understanding Set-PSBreakpoint in PowerShell

Welcome back to Wahmans PowerShell Blog! Today we are diving into a versatile debugging cmdlet: Set-PSBreakpoint. This powerful-tool allows you to pause script execution at a specific line, command, or when a specific variable changes. It’s extremely useful when you’re troubleshooting complex scripts or learning how different parts of your code work.

According to Microsoft, Set-PSBreakpoint “Sets a breakpoint on a line, command, or variable.” Let’s explore how to put it to use in your PowerShell toolbelt—from beginner-friendly examples to more advanced scenarios.

Example 1: Set a Line Breakpoint (Beginner)

Setting a breakpoint on a specific line in a script file is perfect for diving into your script incrementally.

# myscript.ps1
Write-Output "Start"
$a = 5
$b = $a * 2
Write-Output $b
Write-Output "End"

# Set a line breakpoint on line 4
Set-PSBreakpoint -Script "myscript.ps1" -Line 4

When running myscript.ps1 in the debugger, execution will pause at line 4 so you can inspect variables or step through the code.

Example 2: Command Breakpoint

Suppose you want to pause every time a specific command like Get-Process is called. You can set a command breakpoint like so:

Set-PSBreakpoint -Command "Get-Process"

Now running any script or command using Get-Process will trigger the breakpoint allowing you to investigate what’s happening.

Example 3: Variable Breakpoint (Intermediate)

Variable breakpoints pause execution when a specific variable is accessed or changed—super useful when tracking down unexpected values.

# myscript.ps1
$a = 1
for ($i = 0; $i -lt 10; $i++) {
    $a = $i * 2
    Write-Output $a
}

# Set a breakpoint when variable $a is written to
Set-PSBreakpoint -Variable a -Mode Write

This pauses execution every time $a is updated, so you can see when and how its value changes.

Example 4: Advanced Debugging with Multiple Breakpoints

Here’s a more advanced example using a combination of breakpoints for comprehensive debugging insight.

# Combine line, command, and variable breakpoints
Set-PSBreakpoint -Script "advancedscript.ps1" -Line 10
Set-PSBreakpoint -Command "Invoke-WebRequest"
Set-PSBreakpoint -Variable "response" -Mode Write

Imagine your script is making API calls. These breakpoints can help you monitor when the request happens and observe how the response is handled.

Conclusion

Whether you’re debugging a small one-liner or a massive automation script, Set-PSBreakpoint offers flexible control over script execution. Combine different types of breakpoints for powerful debugging workflows.

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