Running a PowerShell script from within another script is a foundational skill for automation, DevOps workflows, and system administration. Whether you are modularizing a complex deployment or orchestrating multiple administrative tasks, understanding the nuances of script execution is critical.

There are three primary ways to execute a script from another: the Call Operator (&), Dot-Sourcing (.), and the Start-Process cmdlet. Each serves a distinct purpose regarding how variables are handled, how memory is used, and whether the script runs in the foreground or background.

Quick Reference of Execution Methods

Before diving into the technical mechanics, here is a high-level summary of the most common methods used in professional environments.

Method Syntax Scope Impact Use Case
Call Operator (&) & "C:\Path\Script.ps1" New child scope Running independent tasks without altering the main script environment.
Dot-Sourcing (.) . "C:\Path\Script.ps1" Same scope Importing functions, variables, or configuration files into the current session.
Start-Process Start-Process powershell.exe ... New process/window Running background tasks or scripts that require elevated privileges.
Invoke-Command Invoke-Command -FilePath ... Remote or local runspace Running scripts on remote servers or in a sanitized local environment.

Using the Call Operator for Standard Execution

The Call Operator (&) is the industry-standard way to run a secondary PowerShell script. In my experience building automation for large-scale server clusters, this is the safest method for 90% of tasks because it respects scope boundaries.

How the Call Operator Works

When you use &, PowerShell creates a new "child scope" for the second script. This means any variables created inside the second script are discarded once it finishes. This prevents "variable pollution," where temporary values in a helper script accidentally overwrite important variables in your main orchestration script.

Example Syntax: