PowerShell Scripting

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Introduction

PowerShell is a powerful command-line scripting language. Not only can it run commands interactively, but it can also combine commands into script files to accomplish complex automation tasks.

This article will guide you step by step through the basic skills of PowerShell script development, including:

• How to create and run.ps1scripts
• How to define and use functions
• How to carry out modular development and reuse your script logic

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1. Getting Started with PowerShell Scripts

Creating Script Files (.ps1)

PowerShell script files are plain text files with the.ps1extension, containing a set of PowerShell commands to execute.

Example: hello.ps1

# hello.ps1
Write-Output "Hello from PowerShell script!"

You can use any text editor (VS Code recommended) to create.ps1files.

Execution Policy

For security reasons, Windows by defaultdoes not allow running scripts, so you need to set the execution policy.

View the current policy:

Get-ExecutionPolicy

Temporarily set to allow local scripts to run:

Set-ExecutionPolicy -Scope CurrentUser -ExecutionPolicy RemoteSigned

RemoteSigned: Local scripts can run without a signature, but downloaded scripts must be signed by a trusted publisher.

Running Scripts

Run from the command line:

.\hello.ps1

Specify the PowerShell executor to run:

powershell.exe -File .\hello.ps1
pwsh.exe -File .\hello.ps1   # PowerShell 7+

Right-click "Run with PowerShell" (requires policy settings)

Passing and Handling Parameters

You can define ways to accept external parameters in a script:

Example: Script with parameters greet.ps1

param (
    [string]$name,
    [int]$age
)

Write-Output "你好，$name，你的年龄是 $age 岁。"

Pass parameters when running:

.\greet.ps1 -name "小明" -age 18

Also supports default values and parameter validation:

param (
    [Parameter(Mandatory=$true)]
    [ValidateNotNullOrEmpty()]
    [string]$City = "北京"
)

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2. Using Functions

Function Definition and Invocation

function Say-Hello {
    Write-Output "Hello from function"
}

Say-Hello

Parameter Declaration and Validation

Functions can also have parameters, defined using aparamblock:

function Add-Numbers {
    param (
        [int]$a,
        [int]$b
    )
    return $a + $b
}

Add-Numbers -a 3 -b 5  # 输出 8

Positional parameters can also be used:

function Add {
    param ($x, $y)
    $x + $y
}
Add 10 20

Return Value Handling

PowerShell functions return all output by default (includingWrite-Output）。

It is recommended to usereturnto return explicitly:

function Get-Square {
    param ([int]$num)
    return $num * $num
}

$result = Get-Square -num 6
Write-Output $result

Function Scope

Variables defined inside a function are local variables by default:

function Demo-Scope {
    $message = "Hello"
}
Demo-Scope
Write-Output $message  # 无法访问

To access variables from outside, you can use scope prefixes:

$global:x = 5

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3. Modular Development

What is a PowerShell Module

A module is a collection of multiple functions, scripts, and resources, used to organize code and facilitate reuse.

Common module types:

• Script modules (.psm1）
• Manifest modules (.psd1）
• Binary modules (.dll)

Importing and Using Modules

UseImport-Moduleto import a module:

Import-Module MyModule.psm1

View loaded modules:

Get-Module

Call functions in a module:

Say-Hello

Introduction to PowerShell Gallery

PowerShell GalleryIt is the official module repository for PowerShell, where you can download and install thousands of modules.

Example of installing a module:

Install-Module -Name PSReadLine

Update a module:

Update-Module PSReadLine

Creating a Simple Custom Module

Create a new MyModule.psm1 file and add functions:

# MyModule.psm1
function Greet-User {
    param ([string]$name)
    Write-Output "欢迎你，$name"
}

Import and call it in a script:

Import-Module .\MyModule.psm1
Greet-User -name "小红"

Tip: You can place module files into paths in$env:PSModulePathso the system automatically recognizes them.

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4. Summary

Content	Description
.ps1File	PowerShell script extension, storing commands
param	Used to define script/function parameters
Set-ExecutionPolicy	Controls whether scripts are allowed to run
Function	Encapsulates reusable code, improving structural clarity
Module (.psm1）	Organizes multiple functions, enabling portability
PowerShell Gallery	Official module repository, where you can download third-party modules

Other Extensions