C-style for loop in Bash Scripting - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a C-style for loop in bash scripting?

A C-style for loop in bash uses the syntax: for (( initialization; condition; increment )); do commands; done. It works like the for loop in C language, controlling the loop with a counter variable.

beginner

Write the syntax of a C-style for loop in bash.

for (( i=0; i<10; i++ )); do # commands done

beginner

How does the increment part work in a C-style for loop in bash?

The increment part updates the loop variable after each iteration. For example, i++ adds 1 to i each time the loop runs.

beginner

What will this loop print? for (( i=1; i<=3; i++ )); do echo $i; done

It will print: 1 2 3 Each number on its own line, counting from 1 to 3.

intermediate

Can you use negative increments in a C-style for loop in bash?

Yes, you can. For example, for (( i=5; i>0; i-- )) will count down from 5 to 1.

What is the correct syntax to start a C-style for loop in bash?

A for i in 0 1 2 3 4

B while (( i<5 ))

C for i=0 to 5

D for (( i=0; i<5; i++ ))

The C-style for loop uses double parentheses with initialization, condition, and increment separated by semicolons.

What does the increment part in a C-style for loop do?

A Checks if the loop should continue

B Updates the loop variable after each iteration

C Initializes the loop variable

D Ends the loop

The increment part changes the loop variable, usually increasing or decreasing it, after each loop cycle.

Which of these loops counts down from 3 to 1?

A for (( i=0; i<3; i++ ))

B for (( i=1; i<=3; i++ ))

C for (( i=3; i>0; i-- ))

D for (( i=3; i<0; i++ ))

The loop starts at 3, continues while i>0, and decreases i by 1 each time.

What will this loop print? for (( i=0; i<3; i++ )); do echo $i; done

A 0 1 2

B 1 2 3

C 0 1 2 3

D 1 2

The loop prints 0, then 1, then 2, because it runs while i is less than 3.

Can you use a C-style for loop to loop over a list of strings in bash?

A No, you must use 'for var in list' syntax

B No, C-style loops only work with numbers

C Yes, but only with arrays

D Yes, directly with C-style syntax

C-style for loops are for numeric loops. To loop over strings, use 'for var in list' syntax.

Explain how a C-style for loop works in bash scripting.

Think about how you set a counter, check it, and change it each time.

Write a C-style for loop in bash that counts from 10 down to 1 and prints each number.

Use decrement operator and condition i>=1.