for loop (list-based) in Bash Scripting - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the basic syntax of a list-based for loop in Bash?

A list-based for loop in Bash looks like this:<br>

for item in list; do<br>  commands<br>done

<br>It runs the commands for each item in the list.

beginner

How does a list-based for loop in Bash work?

It takes each item from the list one by one and runs the commands inside the loop for that item.<br>Think of it like checking each item in a shopping list and doing something with it.

beginner

Write a Bash for loop that prints each fruit in the list: apple, banana, cherry.

for fruit in apple banana cherry; do<br>  echo "$fruit"<br>done

<br>This will print each fruit on its own line.

intermediate

Can the list in a Bash for loop be a variable? How?

Yes! You can store the list in a variable and use it like this:<br>

fruits="apple banana cherry"<br>for fruit in $fruits; do<br>  echo "$fruit"<br>done

beginner

What happens if the list in a Bash for loop is empty?

The loop body does not run at all because there are no items to process.<br>It's like having an empty shopping list; you don't do anything.

What does this Bash code do?<br>

for i in 1 2 3; do echo $i; done

A Prints 1, then 2, then 3 each on a new line

B Prints 123 on one line

C Prints the string 'i' three times

D Gives an error because of missing quotes

The loop runs three times, each time echoing the current item (1, then 2, then 3) on its own line.

Which of these is a valid list for a Bash for loop?

A (apple banana cherry)

B "apple,banana,cherry"

C ['apple', 'banana', 'cherry']

D apple banana cherry

In Bash, lists are space-separated words without commas or brackets.

How do you access the current item inside a Bash for loop?

A Using $current

B Using the loop variable name, e.g., $item

C Using $loop

D Using $this

The loop variable holds the current item, so you use its name with $ to access it.

What will this code print?<br>

list="dog cat"<br>for pet in $list; do echo $pet; done

A dog cat

B list

C dog<br>cat

D Nothing

The loop prints each word in the variable list on its own line.

What happens if you run a Bash for loop with an empty list?

A The loop does not run

B The loop runs once with an empty item

C The script crashes

D It prints an error message

If the list is empty, the loop body is skipped because there are no items.

Explain how a list-based for loop works in Bash and give a simple example.

Think about how you would repeat an action for each item in a list.

Describe how to use a variable as a list in a Bash for loop and why it might be useful.

Variables can store lists to make loops easier to manage.