Logical operators (-and, -or, -not) in PowerShell

Introduction

Logical operators help you combine or change true/false conditions in scripts. They let you make decisions based on multiple rules.

Check if two conditions are both true before running a command.

Run a command if at least one of several conditions is true.

Reverse a condition to run code when something is not true.

Filter data by combining multiple checks.

Control script flow with complex true/false logic.

Syntax

PowerShell

condition1 -and condition2
condition1 -or condition2
-not condition

-and means both conditions must be true.

-or means at least one condition must be true.

-not reverses the condition's result.

Examples

This checks if $a is less than 10 and $b is greater than 5. Both must be true.

PowerShell

$a = 5
$b = 10
if ($a -lt 10 -and $b -gt 5) { "Both true" }

This runs if $a equals 3 or $b equals 5. Only one needs to be true.

PowerShell

$a = 3
$b = 2
if ($a -eq 3 -or $b -eq 5) { "At least one true" }

This reverses $flag. If $flag is false, the code runs.

PowerShell

$flag = $false
if (-not $flag) { "Flag is false" }

Sample Program

This script checks if a person is 18 or older and has an ID. If both are true, it allows entry. If no ID, it says ID required. Otherwise, it denies entry.

PowerShell

$age = 20
$hasID = $true
if ($age -ge 18 -and $hasID) {
    Write-Output "Allowed entry"
} elseif (-not $hasID) {
    Write-Output "ID required"
} else {
    Write-Output "Not allowed"
}

Important Notes

Use parentheses to group conditions for clarity, like: if (($a -lt 10) -and ($b -gt 5))

Logical operators work with boolean values: $true or $false.

PowerShell evaluates conditions left to right and stops early if possible (short-circuit).

Summary

-and means both conditions must be true.

-or means at least one condition must be true.

-not reverses a condition's true/false value.