Iterating over arrays in Bash Scripting - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an array in Bash scripting?

An array in Bash is a list of values stored in a single variable. You can access each value by its position number, starting at zero.

beginner

How do you write a simple for loop to iterate over all elements in a Bash array named fruits?

Use: <br>for fruit in "${fruits[@]}"; do<br> echo "$fruit"<br>done<br>This prints each fruit in the array one by one.

beginner

What does ${array[@]} mean in Bash?

It means all elements of the array. When used in a loop, it lets you access each item one by one.

beginner

How can you get the number of elements in a Bash array named colors?

Use ${#colors[@]}. It returns the count of items in the array.

intermediate

Why is it important to quote "${array[@]}" when iterating over arrays in Bash?

Quoting preserves each element as a single item, even if it contains spaces. Without quotes, elements with spaces may split into multiple words.

Which syntax correctly iterates over all elements in a Bash array named items?

A for item in "${items[@]}"; do echo "$item"; done

B for item in ${items}; do echo "$item"; done

C for item in ${items[@]}; do echo $item; done

D for item in items; do echo "$item"; done

Option A correctly uses quotes and ${items[@]} to iterate over all array elements safely.

How do you get the length of a Bash array named my_array?

A ${#my_array[@]}

B ${my_array.length}

C length(my_array)

D count(my_array)

In Bash, ${#array[@]} returns the number of elements in the array.

What happens if you forget to quote "${array[@]}" in a for loop?

A The loop will not run

B Elements with spaces may split into multiple words

C The array will be empty

D It causes a syntax error

Without quotes, elements containing spaces split into separate words, causing unexpected behavior.

Which of these is a valid way to declare an array in Bash?

A array = {apple, banana, cherry}

B array = [apple, banana, cherry]

C array = (apple banana cherry)

D array=(apple banana cherry)

Option D uses the correct Bash syntax for array declaration.

How do you access the first element of a Bash array named list?

A list[0]

B ${list[1]}

C ${list[0]}

D list(0)

Bash arrays start at index 0, so ${list[0]} accesses the first element.

Explain how to iterate over all elements in a Bash array and print each element.

Think about how you loop over a list of items in real life, like reading names from a list.

Describe why quoting array expansions is important when iterating over arrays in Bash.

Imagine reading a list where some names have spaces, like 'New York'.