How to Use Where-Object in PowerShell: Filter Objects Easily

Use Where-Object in PowerShell to filter objects from a collection by specifying a condition script block. It processes each object and returns only those that meet the condition, like Get-Process | Where-Object { $_.CPU -gt 100 } to find processes using more than 100 CPU seconds.

Syntax

The basic syntax of Where-Object is:

• Collection | Where-Object { condition }
• $_ represents the current object in the pipeline.
• The condition is a script block that returns $true or $false.

Only objects where the condition is true are passed through.

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Collection | Where-Object { <condition> }

Example

This example lists all running processes that use more than 100 CPU seconds. It shows how Where-Object filters objects based on a property.

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Get-Process | Where-Object { $_.CPU -gt 100 } | Select-Object -Property Id, ProcessName, CPU

Output

Id    ProcessName       CPU
--    -----------       ---
1234  chrome            150.5
5678  powershell        120.3

Common Pitfalls

Common mistakes when using Where-Object include:

• Forgetting to use $_ to refer to the current object.
• Using assignment = instead of comparison -eq or other operators.
• Not using curly braces { } around the condition.

Example of wrong and right usage:

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# Wrong: missing $_ and using = instead of -eq
Get-Process | Where-Object { CPU = 100 }

# Right: correct comparison and use of $_
Get-Process | Where-Object { $_.CPU -eq 100 }

Quick Reference

Operator	Description	Example
-eq	Equals	{ $_.Name -eq 'notepad' }
-ne	Not equals	{ $_.Id -ne 1234 }
-gt	Greater than	{ $_.CPU -gt 50 }
-lt	Less than	{ $_.Handles -lt 100 }
-like	Wildcard match	{ $_.ProcessName -like '*chrome*' }

Key Takeaways

Use Where-Object to filter collections by conditions in PowerShell pipelines.

Always use $_ to refer to the current object inside the condition script block.

Use comparison operators like -eq, -gt, -lt inside the script block for filtering.

Enclose the condition in curly braces { } to define the script block.

Avoid using assignment (=) instead of comparison operators in conditions.