Understanding Get-Job in PowerShell

Welcome back to Wahmans Powershell blog! Today, we’re diving into one of PowerShell’s incredibly useful cmdlets: Get-Job. This cmdlet allows you to retrieve background jobs that have been started in the current session. Whether you’re managing automation scripts or simply want to keep track of background tasks, Get-Job will become an indispensable part of your scripting toolkit.

What is Get-Job?

According to Microsoft:

Get-Job: Gets PowerShell background jobs that are running in the current session.

Think of a background job as a way to offload processing that doesn’t need to block the rest of your script. You can start a job, let it run in the background, and continue doing other work. Then you can use Get-Job to check on it later or pull the results.

Examples

1. Starting Simple: Listing Jobs

If you’ve started background jobs using Start-Job, you can list them using Get-Job.

# Start a background job
i.e.
Start-Job -ScriptBlock { Get-Process }

# Get all background jobs
Get-Job

This will list all jobs along with their ID, state (e.g., Running, Completed), and command. Perfect for keeping track of your script’s concurrent tasks.

2. Filtering Jobs by State

You can use Where-Object to filter jobs based on their state. Let’s say you want to find only running jobs:

Get-Job | Where-Object {$_.State -eq 'Running'}

This is a handy way to monitor long-running background activities in a large automation script.

3. Getting Job Results

Get-Job only shows metadata, but you can pair it with Receive-Job to fetch the actual results. Here’s a full walkthrough:

# Start a new background job
$job = Start-Job -ScriptBlock { Get-Date; Start-Sleep -Seconds 5; Get-Date }

# Wait for it to finish
Wait-Job -Id $job.Id

# Get the results
Receive-Job -Id $job.Id

This lets you capture output from background jobs. Remember to always receive the job before removing it if you want to keep the result.

4. Clean Up After Yourself

Over time, jobs can pile up in your session. Use Get-Job in conjunction with Remove-Job to maintain a tidy environment:

# Remove all completed jobs
Get-Job | Where-Object {$_.State -eq 'Completed'} | Remove-Job

This keeps your session from being cluttered with old job information that you no longer need.

Wrap-Up

Whether you’re writing interactive scripts or building complex automation workflows, Get-Job is a vital command for monitoring and managing background jobs in PowerShell. From listing tasks to retrieving results and cleaning up completed items, it’s one of those foundational tools you’ll want in your belt.

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