The Pipeline in Depth

In Module 1 you learned that the pipeline passes objects between cmdlets. Now let's master the cmdlets that make the pipeline truly powerful.

Filtering with Where-Object

Where-Object filters objects based on a condition. The $_ variable represents the current object in the pipeline:

Get-Service | Where-Object { $_.Status -eq 'Running' }
Get-Process | Where-Object { $_.CPU -gt 50 }

Selecting Properties with Select-Object

Select-Object picks which properties to display or limits how many objects are returned:

Get-Process | Select-Object Name, CPU, Id -First 5
Get-Service | Select-Object -ExpandProperty Name

Sorting and Grouping

Sort-Object orders results, while Group-Object clusters them by a property value:

Get-Process | Sort-Object CPU -Descending
Get-Service | Group-Object Status

Measuring with Measure-Object

Measure-Object counts items or calculates sums, averages, minimums, and maximums:

Get-Process | Measure-Object -Property CPU -Sum -Average
Get-ChildItem | Measure-Object -Property Length -Sum

ForEach-Object vs foreach

ForEach-Object runs in the pipeline and processes items one at a time as they stream through. The foreach statement collects all items first, then iterates:

# Pipeline version — streams objects
Get-Service | ForEach-Object { $_.DisplayName.ToUpper() }

# Statement version — collects all first, then loops
foreach ($svc in Get-Service) {
    $svc.DisplayName.ToUpper()
}

Chaining It All Together

The real power comes from combining these cmdlets into a single pipeline:

Get-Process |
    Where-Object { $_.CPU -gt 10 } |
    Sort-Object CPU -Descending |
    Select-Object Name, CPU -First 5

This filters processes by CPU usage, sorts them highest-first, and returns the top 5.