PowerShell If ElseIf Else

Conditional statements let a script make decisions. Based on a condition, the script takes one path or another — just like a road fork: if the condition is true, go this way; otherwise, go that way. The if, elseif, and else statements are the most fundamental decision-making tools in PowerShell.

The if Statement

The if statement checks a condition. If the condition is True, it runs the code block inside the curly braces. If the condition is False, it skips that block.

Syntax

if (condition) {
    # Code runs only when condition is True
}

Example

$temperature = 38

if ($temperature -gt 35) {
    Write-Host "It is very hot today."
}

Output:

It is very hot today.

The if-else Statement

The else block runs when the if condition is False. It handles the "otherwise" scenario.

  Condition Check
        |
        v
   True? ----YES----> Run if block
        |
        NO
        |
        v
   Run else block

$marks = 45

if ($marks -ge 50) {
    Write-Host "Result: Pass"
} else {
    Write-Host "Result: Fail"
}

Output:

Result: Fail

The if-elseif-else Statement

Use elseif to check multiple conditions in sequence. PowerShell evaluates each condition from top to bottom and runs only the first matching block.

  Check Condition 1
        |
   True? --> Run Block 1 --> Done
        |
   False
        |
  Check Condition 2
        |
   True? --> Run Block 2 --> Done
        |
   False
        |
   Run else Block --> Done

$score = 78

if ($score -ge 90) {
    Write-Host "Grade: A"
} elseif ($score -ge 80) {
    Write-Host "Grade: B"
} elseif ($score -ge 70) {
    Write-Host "Grade: C"
} elseif ($score -ge 60) {
    Write-Host "Grade: D"
} else {
    Write-Host "Grade: F"
}

Output:

Grade: C

Multiple Conditions with Logical Operators

$age    = 22
$hasID  = $true

# Both conditions must be true
if ($age -ge 18 -and $hasID) {
    Write-Host "Entry granted"
} else {
    Write-Host "Entry denied"
}

# At least one condition must be true
$isAdmin   = $false
$isSupport = $true

if ($isAdmin -or $isSupport) {
    Write-Host "Access to support dashboard allowed"
}

Output:

Entry granted
Access to support dashboard allowed

Negation with -not

$serviceName = "wuauserv"
$service     = Get-Service -Name $serviceName

if (-not ($service.Status -eq "Running")) {
    Write-Host "$serviceName is NOT running. Starting it now..."
    Start-Service -Name $serviceName
} else {
    Write-Host "$serviceName is already running."
}

Checking Null and Empty Values

$userInput = ""

if ([string]::IsNullOrWhiteSpace($userInput)) {
    Write-Host "Input is empty. Please enter a value."
} else {
    Write-Host "Input received: $userInput"
}

Output:

Input is empty. Please enter a value.

Checking File and Folder Existence

$folderPath = "C:\Reports"

if (Test-Path $folderPath) {
    Write-Host "Folder exists: $folderPath"
} else {
    Write-Host "Folder not found. Creating it..."
    New-Item -Path $folderPath -ItemType Directory
    Write-Host "Folder created."
}

Nested if Statements

An if block can contain another if statement inside it. This handles multi-level conditions.

$userRole = "Admin"
$isActive = $true

if ($userRole -eq "Admin") {
    if ($isActive) {
        Write-Host "Active Admin: Full access granted"
    } else {
        Write-Host "Inactive Admin: Account locked"
    }
} else {
    Write-Host "Standard user: Limited access"
}

Output:

Active Admin: Full access granted

Inline if – Ternary-Style Using Conditional Expression

PowerShell 7 introduced the ternary operator for simple one-line decisions.

# Syntax: condition ? valueIfTrue : valueIfFalse
$age    = 20
$status = $age -ge 18 ? "Adult" : "Minor"
Write-Host $status    # Adult

For PowerShell 5.1 compatibility, use the if expression pattern:

$isOnline = $true
$label    = if ($isOnline) { "Online" } else { "Offline" }
Write-Host $label    # Online

Comparing Strings in Conditions

$environment = "Production"

if ($environment -eq "Production") {
    Write-Host "WARNING: Running in Production!"
} elseif ($environment -eq "Staging") {
    Write-Host "Running in Staging environment."
} else {
    Write-Host "Running in Development environment."
}

Output:

WARNING: Running in Production!

Real-World Example – Disk Space Check

$drive     = Get-PSDrive -Name C
$freeGB    = [math]::Round($drive.Free / 1GB, 2)

Write-Host "Free disk space on C: $freeGB GB"

if ($freeGB -lt 5) {
    Write-Host "CRITICAL: Less than 5 GB free. Take action immediately!" -ForegroundColor Red
} elseif ($freeGB -lt 20) {
    Write-Host "WARNING: Disk space is running low." -ForegroundColor Yellow
} else {
    Write-Host "Disk space is healthy." -ForegroundColor Green
}

Common Mistakes and Fixes

Summary

The if statement is the primary decision-making tool in PowerShell. The else block handles the default case when no condition matches. Multiple elseif blocks handle complex branching logic. Logical operators -and and -or combine conditions in a single check. The ternary operator in PowerShell 7 writes simple decisions on one line. Real-world scripts use conditionals constantly — for service checks, file existence tests, input validation, and environment-specific behavior.