PowerShell Scripting: Automate Windows Administration

PowerShell is the most powerful tool in a Windows admin's arsenal. This guide covers practical scripts you'll use every day.

Getting Started

# Check PowerShell version
$PSVersionTable.PSVersion
Set execution policy (required once)
Set-ExecutionPolicy RemoteSigned -Scope CurrentUser

System Information

# Quick system overview
Get-ComputerInfo | Select-Object CsName, OsName, OsVersion, CsProcessors, CsTotalPhysicalMemory
Disk space report
Get-WmiObject Win32_LogicalDisk |
    Select-Object DeviceID,
    @{N='Size(GB)';E={[math]::Round($_.Size/1GB,2)}},
    @{N='Free(GB)';E={[math]::Round($_.FreeSpace/1GB,2)}},
    @{N='Free%';E={[math]::Round($_.FreeSpace/$_.Size*100,1)}}
Uptime
(Get-Date) - (Get-CimInstance Win32_OperatingSystem).LastBootUpTime

User Management

# List all AD users
Get-ADUser -Filter * -Properties LastLogonDate |
    Select-Object Name, SamAccountName, LastLogonDate, Enabled |
    Sort-Object LastLogonDate -Descending
Find inactive users (90+ days)
$cutoff = (Get-Date).AddDays(-90)
Get-ADUser -Filter {LastLogonDate -lt $cutoff -and Enabled -eq $true} -Properties LastLogonDate |
    Select-Object Name, SamAccountName, LastLogonDate
Create a new AD user
New-ADUser -Name "John Doe" -SamAccountName "jdoe" -UserPrincipalName "[email protected]" 
    -Path "OU=Users,DC=domain,DC=com" -AccountPassword (ConvertTo-SecureString "P@ssw0rd123!" -AsPlainText -Force) 
    -Enabled $true -ChangePasswordAtLogon $true
Bulk create users from CSV
Import-Csv users.csv | ForEach-Object {
    New-ADUser -Name "$($_.FirstName) $($_.LastName)" 
        -SamAccountName $_.Username 
        -UserPrincipalName "$($_.Username)@domain.com" 
        -AccountPassword (ConvertTo-SecureString $_.Password -AsPlainText -Force) 
        -Enabled $true
}

Service Management

# Check service status
Get-Service | Where-Object {$_.Status -eq 'Running'} | Sort-Object DisplayName
Restart a service
Restart-Service -Name "Spooler" -Force
Monitor a service and restart if stopped
$service = "ImportantService"
if ((Get-Service $service).Status -ne 'Running') {
    Start-Service $service
    Send-MailMessage -To "[email protected]" -Subject "$service was restarted" 
        -Body "Service was found stopped and restarted at $(Get-Date)" 
        -SmtpServer "mail.company.com"
}

Log Analysis

# Find failed login attempts
Get-WinEvent -FilterHashtable @{LogName='Security'; Id=4625} -MaxEvents 50 |
    Select-Object TimeCreated,
    @{N='User';E={$_.Properties[5].Value}},
    @{N='Source';E={$_.Properties[19].Value}}
Check for errors in the last 24 hours
Get-WinEvent -FilterHashtable @{LogName='System'; Level=2; StartTime=(Get-Date).AddDays(-1)} |
    Select-Object TimeCreated, ProviderName, Message | Format-Table -Wrap
Export events to CSV
Get-WinEvent -FilterHashtable @{LogName='Application'; Level=2,3} -MaxEvents 100 |
    Export-Csv "C:\logs\app-errors.csv" -NoTypeInformation

Network Diagnostics

# Check open ports
Get-NetTCPConnection -State Listen |
    Select-Object LocalPort, OwningProcess,
    @{N='Process';E={(Get-Process -Id $_.OwningProcess).Name}} |
    Sort-Object LocalPort
DNS lookup
Resolve-DnsName google.com -Type A
Ping sweep a subnet
1..254 | ForEach-Object -Parallel {
    if (Test-Connection "192.168.1.$_" -Count 1 -Quiet -TimeoutSeconds 1) {
        "192.168.1.$_ is alive"
    }
} -ThrottleLimit 50

Practical Scripts

Daily report email:

$report = @"
Server: $env:COMPUTERNAME
Date: $(Get-Date)
Uptime: $((Get-Date) - (Get-CimInstance Win32_OperatingSystem).LastBootUpTime)
CPU: $((Get-Counter '\Processor(_Total)\% Processor Time').CounterSamples.CookedValue)%
Free Disk: $([math]::Round((Get-WmiObject Win32_LogicalDisk -Filter "DeviceID='C:'").FreeSpace/1GB,2))GB
"@
Send-MailMessage -To "[email protected]" -Subject "Daily Report - $env:COMPUTERNAME" `
    -Body $report -SmtpServer "mail.company.com"

Conclusion

These scripts handle 80% of daily Windows admin tasks. Save them in a scripts folder, customize for your environment, and schedule the recurring ones with Task Scheduler. PowerShell turns hours of clicking into seconds of automation.