Function

🔧 What is a function?

A function is a block of code that:

• performs a specific task
• can be reused
• reduces code duplication

🔹 Function syntax

function_name () {
    commands
}

OR

function function_name {
    commands
}

✅ Example 1: Simple function (EXAM BASIC ⭐)

#!/bin/bash

greet () {
    echo "Hello Linux"
}

greet

✅ Example 2: Function with arguments

#!/bin/bash

add () {
    sum=$(( $1 + $2 ))
    echo "Sum = $sum"
}

add 10 20

✅ Example 3: Function returning value (using echo)

#!/bin/bash

square () {
    echo $(( $1 * $1 ))
}

result=$(square 5)
echo "Square = $result"

✅ Example 4: Function to check even or odd

#!/bin/bash

check () {
    if [ $(( $1 % 2 )) -eq 0 ]; then
        echo "Even number"
    else
        echo "Odd number"
    fi
}

check 7

✅ Example 5: Function using global variable

#!/bin/bash

x=10

show () {
    echo "Value of x = $x"
}

show

✅ Example 6: Function with local variable

#!/bin/bash

display () {
    local msg="Linux OS"
    echo $msg
}

display

✅ Example 7: Function + array

#!/bin/bash

print_array () {
    echo ${arr[@]}
}

arr=(1 2 3 4)
print_array