Functions

Simple function with parameter

#!/bin/bash
function greet() {
    echo "Hello, $1!"
}

greet "World"

Function that returns a value

#!/bin/bash
function add() {
    local result=$(( $1 + $2 ))
    echo $result
}

sum=$(add 5 3)
echo "Sum is: $sum"

Function with local variables and error handling

#!/bin/bash
function process_file() {
    local filename=$1
    local temp_file="/tmp/processed_$filename"
    
    if [ -f "$filename" ]; then
        echo "Processing $filename"
        # Process file here
    else
        echo "File $filename not found"
        return 1
    fi
}

Function with default parameter values

#!/bin/bash
greet() {
    local name=${1:-"World"}
    local greeting=${2:-"Hello"}
    echo "$greeting, $name!"
}

greet
greet "Alice"
greet "Bob" "Hi"

Function that accepts variable number of arguments

#!/bin/bash
sum() {
    local total=0
    for num in "$@"; do
        total=$((total + num))
    done
    echo $total
}

result=$(sum 1 2 3 4 5)
echo "Sum: $result"

Function with error handling and return codes

#!/bin/bash
safe_divide() {
    if [ $2 -eq 0 ]; then
        echo "Error: Division by zero" >&2
        return 1
    fi
    echo $(( $1 / $2 ))
}

result=$(safe_divide 10 2)
echo "Result: $result"

safe_divide 10 0

Recursive function example

#!/bin/bash
factorial() {
    local n=$1
    if [ $n -le 1 ]; then
        echo 1
    else
        local prev=$(factorial $((n-1)))
        echo $((n * prev))
    fi
}

echo "Factorial of 5: $(factorial 5)"