Arrays

A Bash array holds a list of values under one name, indexed from zero, and it comes with its own small family of special expansions worth knowing by heart.

Creating and reading an array

bash fruits.sh

#!/bin/bash
fruits=("apple" "banana" "cherry")

echo "${fruits[0]}"
echo "${fruits[2]}"
echo "Total: ${#fruits[@]}"

Terminal output

apple
cherry
Total: 3

${fruits[0]} reads a single element (indexing starts at 0), and ${#fruits[@]} gives the number of elements — the curly braces around every array expansion aren't optional.

Looping over an array

bash loop-fruits.sh

#!/bin/bash
fruits=("apple" "banana" "cherry")

for fruit in "${fruits[@]}"; do
    echo "- $fruit"
done

Terminal output

- apple
- banana
- cherry

Adding elements

bash append.sh

#!/bin/bash
fruits=("apple" "banana")
fruits+=("cherry")

echo "${fruits[@]}"

Terminal output

apple banana cherry

@ vs *, again: just like "$@" with script arguments, "${fruits[@]}" (quoted) expands each element as its own separate word — safe even if an element contains spaces — while "${fruits[*]}" joins everything into one string. Use "${arr[@]}" when looping.

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