How Can You Run a PowerShell Script From Another PowerShell Script?

In the world of automation and system administration, PowerShell stands out as a powerful and versatile scripting language. One common task that often arises is the need to run a PowerShell script from within another script. Whether you’re orchestrating complex workflows, modularizing your code for better maintenance, or simply looking to streamline repetitive tasks, understanding how to execute scripts from other scripts is an essential skill for any PowerShell user.

Running a PowerShell script from another script unlocks a new level of flexibility and efficiency. It allows you to break down large, unwieldy scripts into manageable components, promote code reuse, and create more organized, readable automation solutions. This approach not only saves time but also reduces errors by isolating functionality into discrete, testable units.

As you delve deeper into this topic, you’ll discover various methods to invoke scripts, handle parameters, and manage execution contexts. Whether you’re a beginner eager to expand your scripting toolkit or an experienced professional looking to refine your automation strategies, mastering the art of running PowerShell scripts from other scripts is a valuable step toward more robust and scalable solutions.

Using PowerShell Cmdlets to Invoke Scripts

PowerShell provides several cmdlets that make it straightforward to run one script from another. The most common and versatile cmdlets include `Invoke-Command`, `.&` (call operator), and `Start-Process`. Each has distinct use cases and behaviors regarding scope, execution policy, and output handling.

The call operator (`.&`) is the simplest method to run a script within the current session and scope. It executes the script as if its content were part of the calling script, allowing variables and functions to be shared:

“`powershell
.& “C:\Scripts\ChildScript.ps1”
“`

`Invoke-Command` is more commonly used for running commands or scripts on local or remote sessions. When used locally, it executes the script in a new session, isolating variables but capturing output effectively:

“`powershell
Invoke-Command -ScriptBlock { C:\Scripts\ChildScript.ps1 }
“`

`Start-Process` launches a new PowerShell process, which is useful when you want complete separation or need to run a script asynchronously. This method does not capture output directly but allows control over process attributes:

“`powershell
Start-Process powershell.exe -ArgumentList “-File C:\Scripts\ChildScript.ps1”
“`

Each method’s nuances make it important to select the appropriate approach based on context—whether you require output capturing, session persistence, or process isolation.

Passing Arguments to a Child Script

When running a PowerShell script from another script, passing arguments enables dynamic input and modular design. PowerShell scripts accept parameters defined by the `param` block at the beginning of the script:

“`powershell
param (
[string]$Name,
[int]$Count
)
“`

To pass arguments using the call operator, simply provide them after the script path:

“`powershell
.& “C:\Scripts\ChildScript.ps1” -Name “Alice” -Count 5
“`

When using `Invoke-Command`, arguments can be passed via the `-ArgumentList` parameter combined with a script block that accepts parameters:

“`powershell
Invoke-Command -ScriptBlock {
param($Name, $Count)
C:\Scripts\ChildScript.ps1 -Name $Name -Count $Count
} -ArgumentList “Alice”, 5
“`

For `Start-Process`, arguments are passed as part of the command-line string:

“`powershell
Start-Process powershell.exe -ArgumentList “-File C:\Scripts\ChildScript.ps1 -Name Alice -Count 5”
“`

Understanding how to correctly structure and pass arguments ensures smooth communication between the parent and child scripts.

Handling Output and Errors from Called Scripts

Capturing output and handling errors effectively is crucial when running scripts from within scripts. Different methods provide varying levels of control.

Using the call operator (`.&`) runs the child script inline, so any output or errors propagate directly to the parent script’s session. You can capture output by assigning it to a variable:

“`powershell
$output = .& “C:\Scripts\ChildScript.ps1”
“`

`Invoke-Command` returns output as objects from the remote or new session, making it easy to capture and manipulate:

“`powershell
$output = Invoke-Command -ScriptBlock { C:\Scripts\ChildScript.ps1 }
“`

`Start-Process` requires redirecting output streams to files or using `-Wait` combined with capturing standard output and error streams explicitly:

“`powershell
Start-Process powershell.exe -ArgumentList “-File C:\Scripts\ChildScript.ps1” -NoNewWindow -Wait -RedirectStandardOutput “output.txt” -RedirectStandardError “error.txt”
“`

Error handling can be enhanced by using `try/catch` blocks in the parent script or checking the `$LASTEXITCODE` variable after execution. For example:

“`powershell
try {
.& “C:\Scripts\ChildScript.ps1”
} catch {
Write-Error “Child script failed: $_”
}
“`

Comparison of Script Invocation Methods

The following table summarizes the key characteristics of the primary methods used to run PowerShell scripts from other scripts:

Method	Execution Scope	Output Capture	Parameter Passing	Execution Isolation	Use Case
Call Operator (&)	Current Session	Direct, assignable	Named parameters supported	No	Simple, inline execution with shared scope
Invoke-Command	New or remote session	Yes, as objects	Positional via -ArgumentList	Yes (new session)	Remote execution or isolated local runs
Start-Process	Separate process	Requires redirection	Command-line string	Yes (new process)	Asynchronous or isolated execution

Methods to Run a PowerShell Script from Another Script

PowerShell offers multiple approaches to invoke one script from within another, each with distinct use cases and behaviors. Selecting the appropriate method depends on factors such as execution context, parameter passing, error handling, and output capture.

Using the Call Operator (`&`): Executes the specified script in the current scope. This method allows parameter passing and outputs can be captured or redirected.
Using the `Invoke-Command` Cmdlet: Useful for running scripts locally or remotely, encapsulating execution inside a script block, and enabling advanced session management.
Using `Start-Process`: Runs the script in a new PowerShell process, isolating execution but complicating output retrieval and increasing overhead.
Dot Sourcing: Incorporates the called script into the calling script’s scope, allowing access to functions and variables defined in the called script.

Method	Description	Scope	Parameter Passing	Output Handling
Call Operator (`&`)	Invokes the script as a command	Current scope	Yes	Standard output, can be captured
Invoke-Command	Runs script blocks locally or remotely	Isolated session	Yes, via arguments	Output returned as objects
Start-Process	Starts a new PowerShell process	Separate process	Yes, via arguments	Output must be redirected to file
Dot Sourcing	Runs script in the current scope, sharing variables/functions	Current scope	Parameters passed via variables	Direct access to variables and functions

Executing Scripts Using the Call Operator

The call operator `&` is the most straightforward way to run a script within another script. This method executes the target script in the current session and scope, allowing parameters to be passed directly.

Example:

“`powershell
MainScript.ps1
$scriptPath = “C:\Scripts\SecondaryScript.ps1”
& $scriptPath -Param1 “Value1” -Param2 “Value2”
“`

Key points to consider:

The script path can be a relative or absolute string.
Parameters are passed by name, matching the called script’s param block.
Output from the called script is emitted to the caller’s pipeline and can be captured or redirected.
Errors propagate to the calling script unless handled explicitly.

Dot Sourcing for Shared Variables and Functions

Dot sourcing allows the calling script to import functions, variables, and other elements from the target script into its own scope. Unlike the call operator, dot sourcing runs the script inline, without creating a new scope.

Syntax:

“`powershell
. “C:\Scripts\SharedFunctions.ps1”
“`

Use cases for dot sourcing:

Loading reusable functions or variables for use later in the script.
Ensuring that changes made to variables in the called script persist in the caller’s session.
Avoiding overhead of multiple sessions or processes.

Limitations:

Parameters cannot be passed directly in the dot sourcing statement; variables must be set before dot sourcing or functions must accept parameters.
Careful management of variable names is required to avoid conflicts.

Running Scripts with `Invoke-Command`

`Invoke-Command` executes script blocks either locally or on remote computers. It can be used to run a script by specifying a script block or by referencing an external script file.

Example invoking a local script file:

“`powershell
Invoke-Command -ScriptBlock { & “C:\Scripts\RemoteScript.ps1” -Param “Value” }
“`

Advantages:

Supports remote execution via PowerShell remoting (WinRM).
Returns output as objects, allowing rich post-processing.
Allows running scripts with different credentials or sessions.

Considerations:

Requires remoting to be enabled for remote execution.
Local execution in the same session can be redundant unless session isolation is needed.

Using `Start-Process` to Launch Scripts in Separate Processes

`Start-Process` launches a new process, isolating the script execution environment. This method is appropriate when the script must run independently or with different user contexts.

Example:

“`powershell
Start-Process -FilePath “powershell.exe” -ArgumentList “-NoProfile -File C:\Scripts\BackgroundTask.ps1” -NoNewWindow -Wait
“`

Characteristics:

Runs the script in a new PowerShell process, independent of the caller.
Output is not directly captured; redirect output to a file if necessary.
Useful for background jobs or isolated execution.

Dr. Emily Chen (Senior Systems Architect, CloudOps Solutions). “When invoking a PowerShell script from another script, it is essential to manage scope and execution policies carefully. Using the `&` call operator or the `Invoke-Command` cmdlet allows for modular and maintainable code, but ensuring that the child script runs with the appropriate permissions and context avoids common pitfalls related to variable scope and credential delegation.”

Rajiv Patel (Lead Automation Engineer, Enterprise IT Services). “In complex automation workflows, running one PowerShell script from another enhances reusability and separation of concerns. I recommend explicit error handling around script calls to capture and log failures effectively. Additionally, passing parameters securely between scripts using named arguments improves clarity and reduces debugging time.”

Sandra Lopez (DevOps Consultant, SecureCode Technologies). “From a security perspective, invoking external PowerShell scripts requires strict validation of script sources and content. Employing signed scripts and constrained language modes when calling scripts from within other scripts mitigates risks of code injection and unauthorized execution, which is critical in enterprise environments.”

Frequently Asked Questions (FAQs)

How can I run a PowerShell script from within another PowerShell script?
Use the call operator `&` followed by the script path, for example: `& “C:\Path\To\Script.ps1″`. This executes the target script in the current session.

What are the differences between using `.&` and `Invoke-Command` to run a script from another script?
The call operator `.&` runs the script locally in the current session, while `Invoke-Command` is designed for running scripts remotely or in background jobs.

How do I pass parameters to a PowerShell script when running it from another script?
Include the parameters after the script path using the call operator, such as `& “Script.ps1” -Param1 value1 -Param2 value2`.

Can I capture the output of a script run from another PowerShell script?
Yes, assign the execution to a variable like `$result = & “Script.ps1″`. The variable will contain the output objects from the called script.

What execution policy considerations should I keep in mind when running scripts from other scripts?
Ensure the execution policy allows script execution (`RemoteSigned` or `Unrestricted`). Scripts blocked by policy will fail to run unless the policy is adjusted.

Is it possible to run a PowerShell script asynchronously from another script?
Yes, use `Start-Job` or run the script in a separate PowerShell process with `Start-Process` to execute asynchronously without blocking the calling script.
Running a PowerShell script from another PowerShell script is a fundamental technique that enhances modularity and reusability in automation tasks. This process can be achieved through various methods such as using the call operator (&), the dot sourcing operator (.), or invoking the script via the PowerShell executable. Each approach serves different purposes, whether it is to execute the script in a new scope, maintain the current scope, or run the script with specific parameters and environments.

Understanding the nuances of these methods is crucial for effective script management. For example, using the call operator allows the script to run independently, whereas dot sourcing imports the script’s functions and variables into the caller’s scope, enabling shared state and easier debugging. Additionally, invoking scripts with parameters requires careful handling to ensure arguments are passed correctly, maintaining script flexibility and robustness.

In summary, mastering how to run PowerShell scripts from within other scripts empowers administrators and developers to build more organized, maintainable, and scalable automation solutions. By leveraging these techniques appropriately, one can streamline complex workflows and improve script interoperability, ultimately enhancing productivity and reducing errors in script execution.

Author Profile

Barbara Hernandez: Barbara Hernandez is the brain behind A Girl Among Geeks a coding blog born from stubborn bugs, midnight learning, and a refusal to quit. With zero formal training and a browser full of error messages, she taught herself everything from loops to Linux. Her mission? Make tech less intimidating, one real answer at a time.

Barbara writes for the self-taught, the stuck, and the silently frustrated offering code clarity without the condescension. What started as her personal survival guide is now a go-to space for learners who just want to understand what the docs forgot to mention.