ForEach-Object is a PowerShell CmdLet that processes each object coming through the pipeline one at a time. It is the standard way to run a script block against every item in a pipeline stream.

Syntax

<command> | ForEach-Object { <script block using $_> }

• $_ is the automatic variable representing the current object in the pipeline.
• The script block { } is executed once per input object.

Example from the book

The example in the book combines Get-Process and Get-NetTCPConnection into a single pipeline:

Get-Process -Name chrome | ForEach-Object {
    Get-NetTCPConnection -State Established -OwningProcess $_.Id -ErrorAction SilentlyContinue
}

For each Chrome process, the script block uses $_.Id to pass that process's ID to Get-NetTCPConnection.

Alias

% is a shorthand alias for ForEach-Object:

Get-Process -Name chrome | % { $_.Id }

ForEach-Object vs foreach

ForEach-Object is essential for building single-pipeline solutions that avoid intermediate variables.

Common use cases

• Running a command for each object in a pipeline.
• Accessing nested properties of piped objects, similar to Select-Object.
• Building PowerShell Custom Objects from pipeline data.

Example:

Get-Process | ForEach-Object {
    [PSCustomObject]@{
        Name = $_.Name
        Id   = $_.Id
    }
}