Bash — Arrays

Indexed arrays

#!/bin/bash

# Create array
fruits=("Apple" "Banana" "Cherry" "Date")

# Access elements
echo "${fruits[0]}"    # Apple
echo "${fruits[@]}"    # All elements
echo "${#fruits[@]}"   # Length: 4

# Add element
fruits+=("Elder")

# Remove element
unset fruits[1]

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

Associative arrays

#!/bin/bash

declare -A ages
ages[Alice]=30
ages[Bob]=25
ages[Charlie]=35

echo "${ages[Alice]}"    # 30
echo "${!ages[@]}"       # All keys
echo "${ages[@]}"        # All values

# Iterate
for name in "${!ages[@]}"; do
    echo "$name: ${ages[$name]}"
done

Array operations

#!/bin/bash

arr=(1 2 3 4 5)

# Slice
echo "${arr[@]:1:3}"    # 2 3 4

# Replace
echo "${arr[@]/3/99}"   # 1 2 99 4 5

# Join
echo "$(IFS=', '; echo "${arr[*]}")"  # 1,2,3,4,5

Mini Practice

Write Bash code that:

1. Creates and iterates an indexed array
2. Creates an associative array
3. Slices an array
4. Joins array elements with a delimiter

Up Next

In the next lesson, you'll learn about Operators — comparison and logical operators.