PowerShell, with its versatility and scripting capabilities, provides a powerful feature called script blocks. Script blocks are enclosed sections of code that can be executed as a single unit. They are denoted by curly braces {} and can be assigned to variables, passed as parameters, or used with various PowerShell cmdlets and operators.

Basic Syntax

The basic syntax of a script block is as follows:

& {
    # Your code here
}

The ampersand & is the call operator, which is used to invoke the script block. The script block itself is enclosed within curly braces.

When to Use Script Blocks

1. Grouping Commands

Script blocks are handy for grouping multiple commands as a single unit. This is especially useful when you want to execute several commands together. For example:

& {
    $variable1 = "Hello"
    $variable2 = "World"
    Write-Host "$variable1 $variable2"
}

In this case, the script block groups the assignment of variables and the Write-Host command.

2. ForEach-Object Cmdlet

Script blocks are often used with the ForEach-Object cmdlet to perform actions on each item in a collection. Here's an example doubling each number in an array:

$numbers = 1, 2, 3, 4, 5

& {
    $numbers | ForEach-Object {
        $_ * 2
    }
}

3. Passing Parameters

Script blocks can receive parameters, making them versatile for dynamic code execution. Example:

$greet = {
    param($name)
    Write-Host "Hello, $name!"
}

& $greet -name "John"

Using Script Blocks in Batch Scripts

You can integrate PowerShell script blocks into batch scripts using the powershell.exe command. Here's a simple example:

@echo off
setlocal enabledelayedexpansion

set "PowerShellCommand=$numbers = 1, 2, 3, 4, 5; $numbers | ForEach-Object { $_ * 2 }"

for /f "delims=" %%i in ('powershell -Command "!PowerShellCommand!"') do (
    echo Doubled number: %%i
)

endlocal

This batch script utilizes a PowerShell script block to double each number in an array.

Conclusion

Understanding PowerShell script blocks opens up a range of possibilities for code organization, iteration, and dynamic execution. Whether you're grouping commands, iterating through a collection, or passing parameters dynamically, script blocks are a valuable tool in PowerShell scripting. Experimenting with different use cases will enhance your PowerShell scripting skills and help you streamline your automation tasks.