Where-Object for filtering in PowerShell - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the <code>Where-Object</code> cmdlet do in PowerShell?

Where-Object filters objects from a collection based on a condition you specify. It only passes through objects that meet the condition.

beginner

How do you write a simple Where-Object filter to get numbers greater than 10 from a list?

Use: ... | Where-Object { $_ -gt 10 }. Here, $_ is the current item, and -gt means 'greater than'.

beginner

What does $_ represent inside the Where-Object script block?

$_ is a variable that holds the current object being tested in the filter. Think of it as 'this item' in the list.

intermediate

Can Where-Object filter based on object properties? Give an example.

Yes. For example, to filter processes using more than 100MB memory: Get-Process | Where-Object { $_.WorkingSet -gt 100MB }.

intermediate

What is the difference between Where-Object and ForEach-Object?

Where-Object filters items based on a condition. ForEach-Object runs a command on each item but does not filter.

What does Where-Object { $_ -eq 5 } do?

A Selects objects equal to 5

B Selects objects not equal to 5

C Selects all objects

D Deletes objects equal to 5

The condition $_ -eq 5 means 'equal to 5', so it selects only those objects.

In Where-Object, what does $_ stand for?

A The script name

B A global variable

C The last command run

D The current object in the pipeline

$_ is the current object being processed in the pipeline.

Which operator filters objects greater than 100 in Where-Object?

A -lt

B -eq

C -gt

D -ne

-gt means 'greater than'.

How would you filter files larger than 1MB using Where-Object?

A Get-ChildItem | Where-Object { $_ -eq 1MB }

B Get-ChildItem | Where-Object { $_.Length -gt 1MB }

C Get-ChildItem | Where-Object { $_.Size -lt 1MB }

D Get-ChildItem | Where-Object { $_.Length -lt 1MB }

Length is the file size property, and -gt 1MB filters files larger than 1MB.

Which cmdlet would you use to run a command on each object without filtering?

A ForEach-Object

B Where-Object

C Select-Object

D Sort-Object

ForEach-Object runs commands on each object but does not filter.

Explain how Where-Object works to filter items in a PowerShell pipeline.

Think about how you pick only certain fruits from a basket based on color.

Describe how to filter processes that use more than 50MB of memory using Where-Object.

Remember to check the property that shows memory usage.