Pipeline input (ValueFromPipeline) in PowerShell - Mini Project: Build & Apply

Using Pipeline Input with ValueFromPipeline in PowerShell

📖 Scenario: You are automating a task where you want to process a list of file names. Instead of passing each file name manually, you want to send them through the pipeline to a function that processes each file.

🎯 Goal: Create a PowerShell function that accepts file names from the pipeline using ValueFromPipeline and then outputs a message for each file.

📋 What You'll Learn

Create a function named Process-File that accepts a parameter FileName from the pipeline.

Use the ValueFromPipeline attribute to enable pipeline input.

Inside the function, output a message that says: Processing file: <FileName>.

Send a list of file names through the pipeline to the function.

Print the output messages for each file.

💡 Why This Matters

🌍 Real World

PowerShell scripts often process lists of items like files, users, or services. Using pipeline input makes scripts flexible and easy to chain commands.

💼 Career

Understanding pipeline input is essential for system administrators and automation engineers who write PowerShell scripts to automate tasks efficiently.

1

Create a list of file names

Create a variable called files and assign it an array with these exact file names: "report1.txt", "data.csv", "image.png".

PowerShell

# Create the array variable files with the specified file names
# Your code here

Need a hint?

Use @() to create an array in PowerShell.

2

Define the function with pipeline input

Define a function named Process-File with a parameter FileName that accepts pipeline input using the attribute [Parameter(ValueFromPipeline=$true)].

PowerShell

$files = @("report1.txt", "data.csv", "image.png")

# Define the function Process-File with pipeline input
# Your code here

Need a hint?

Use param() block inside the function to define parameters.

3

Add processing logic inside the function

Inside the Process-File function, add a process block that outputs the message Processing file: <$FileName> using Write-Output.

PowerShell

$files = @("report1.txt", "data.csv", "image.png")

function Process-File {
    param(
        [Parameter(ValueFromPipeline=$true)]
        [string]$FileName
    )
    # Add process block to output the message
    # Your code here
}

Need a hint?

The process block runs once for each pipeline input object.

4

Send the file names through the pipeline and display output

Send the files array through the pipeline to the Process-File function and print the output messages.

PowerShell

$files = @("report1.txt", "data.csv", "image.png")

function Process-File {
    param(
        [Parameter(ValueFromPipeline=$true)]
        [string]$FileName
    )
    process {
        Write-Output "Processing file: $FileName"
    }
}

# Send files through pipeline to Process-File and print output
# Your code here

Need a hint?

Use the pipeline operator | to send files to Process-File.