PowerShell Practical Applications

PowerShell is not just a terminal tool; it is one of the most comprehensive automation platforms in the Windows environment.

This section will usethree major categories of practical application scenariosto demonstrate PowerShell's powerful capabilities in daily management, remote operations, and cross-technology integration:

• Daily management task automation
• Remote management
• Integration with other technologies

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1. Daily Management Task Automation

1.1 Batch File Renaming

Requirement:

All files in a directory.txtare renamed to the format of a unified prefix plus a sequence number, such as:log_001.txt、log_002.txtetc.

Example code:

$files = Get-ChildItem -Path "D:\Logs" -Filter "*.txt"
$count = 1
foreach ($file in $files) {
    $newName = "log_{0:D3}.txt" -f $count
    Rename-Item -Path $file.FullName -NewName $newName
    $count++
}

Scheduled Cleanup of Temporary Files

Example: Delete temporary files older than 7 days

$targetPath = "C:\Windows\Temp"
Get-ChildItem -Path $targetPath -Recurse |
    Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-7) } |
    Remove-Item -Force -Recurse

It is recommended to save the script as.ps1a file, and then use Task Scheduler to run it periodically.

System Information Collection Script

$info = [PSCustomObject]@{
    ComputerName = $env:COMPUTERNAME
    OSVersion    = (Get-CimInstance Win32_OperatingSystem).Caption
    Uptime       = ((Get-Date) - (Get-CimInstance Win32_OperatingSystem).LastBootUpTime).ToString()
    CPU          = (Get-CimInstance Win32_Processor).Name
    RAM_GB       = [math]::Round((Get-CimInstance Win32_ComputerSystem).TotalPhysicalMemory / 1GB, 2)
}
$info | Format-List

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Log Analysis and Report Generation

$logPath = "C:\inetpub\logs\LogFiles\W3SVC1\*.log"
$lines = Get-Content $logPath | Where-Object { $_ -match "500" }

$lines.Count
$lines | Out-File "C:\Reports\error_500_report.txt"

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2. Remote Management

PowerShell Remoting Basics

PowerShell Remoting is a mechanism for executing remote commands via WinRM.

Enable remote functionality (run as administrator):

Enable-PSRemoting -Force

UsageInvoke-CommandExecute Remote Commands

Invoke-Command -ComputerName "Server01" -ScriptBlock {
    Get-Service -Name "W32Time"
}

Supports batch execution on multiple hosts:

$servers = @("Server01", "Server02")
Invoke-Command -ComputerName $servers -ScriptBlock {
    Get-Process | Where-Object { $_.CPU -gt 100 }
}

Remote Session Management

Create a session:

$session = New-PSSession -ComputerName "Server01"

Enter the session:

Enter-PSSession $session

Execute commands:

Invoke-Command -Session $session -ScriptBlock { Get-Date }

Close the session:

Remove-PSSession $session

Security Considerations

• Use HTTPS instead of HTTP (configure certificates)
• Avoid using plaintext passwords; it is recommended to use credential objects:

$cred = Get-Credential
Invoke-Command -ComputerName "Server01" -Credential $cred -ScriptBlock { hostname }

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3. Integration with Other Technologies

PowerShell and .NET Framework

PowerShell has built-in access to .NET class libraries and can call almost all .NET APIs.

Example: Get the MD5 value of a file

function Get-FileHashMD5 {
    param ([string]$path)
    $md5 = [System.Security.Cryptography.MD5]::Create()
    $bytes = [System.IO.File]::ReadAllBytes($path)
    $hash = $md5.ComputeHash($bytes)
    return ([BitConverter]::ToString($hash)).Replace("-", "")
}

Get-FileHashMD5 "D:\file.zip"

Calling REST APIs

Example: Call a JSON API to get weather information

$response = Invoke-RestMethod -Uri "https://api.weatherapi.com/v1/current.json?key=APIKEY&q=Beijing"
$response.location.name
$response.current.temp_c

Database Connection Basics (Example: SQL Server)

$connectionString = "Server=localhost;Database=TestDB;Integrated Security=True"
$query = "SELECT TOP 10 * FROM Users"

$connection = New-Object System.Data.SqlClient.SqlConnection $connectionString
$command = $connection.CreateCommand()
$command.CommandText = $query

$connection.Open()
$reader = $command.ExecuteReader()
while ($reader.Read()) {
    Write-Output $reader["UserName"]
}
$connection.Close()

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Interacting with Office Applications

Example: Use the Excel COM object to write data

$excel = New-Object -ComObject Excel.Application
$excel.Visible = $true
$workbook = $excel.Workbooks.Add()
$sheet = $workbook.Worksheets.Item(1)

$sheet.Cells.Item(1, 1) = "Name"
$sheet.Cells.Item(1, 2) = "Score"
$sheet.Cells.Item(2, 1) = "Alice"
$sheet.Cells.Item(2, 2) = 95

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4. Summary

Application Type	Practical Use	Technical Points
Local Automation	Batch renaming, file cleanup, system information	File system, timers, objects
Log Analysis	Check error logs and generate reports	Text processing, filtering, exporting
Remote Operations	Batch operations on multiple hosts, remote sessions	Invoke-Command, PSSession
Technical Integration	Integration with REST APIs, databases, and Excel	Invoke-RestMethod, COM, ADO.NET
.NET Support	Call underlying APIs to implement extended functionality	Use .NET class libraries

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