for loop (list-based) in Bash Scripting - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to loop over the list of fruits and print each one.

Bash Scripting

for fruit in [1]; do
  echo "$fruit"
done

Drag options to blanks, or click blank then click option'

A(apple banana cherry)

B"apple banana cherry"

Capple banana cherry

D[apple banana cherry]

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around the list makes it a single string, not a list.

Using parentheses or brackets is not valid for list iteration in bash.

In bash, to loop over a list of words, you write them separated by spaces without quotes or parentheses.

2fill in blank

medium

Complete the code to loop over the list and print each item in uppercase.

Bash Scripting

for item in apple banana cherry; do
  [1] "$item"
done

Drag options to blanks, or click blank then click option'

Aprintf

Becho

Ccut

Dtr '[:lower:]' '[:upper:]' <<<

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'echo' alone does not change case.

Using 'cut' does not change letter case.

Using 'tr' with input redirection converts the text to uppercase.

3fill in blank

hard

Fix the error in the loop to correctly iterate over the list and print each element.

Bash Scripting

for i in [1]; do
  echo "$i"
done

Drag options to blanks, or click blank then click option'

A"apple banana cherry"

Bapple banana cherry

Capple,banana,cherry

D(apple banana cherry)

Attempts:

3 left

💡 Hint

Common Mistakes

Using commas breaks the list into one string.

Using quotes makes the entire list one item.

The list should be space-separated words without quotes or commas for bash to iterate correctly.

4fill in blank

hard

Fill both blanks to create a loop that prints only fruits with names longer than 5 letters.

Bash Scripting

for fruit in apple banana cherry date; do
  if [[ ${#fruit} [1] 5 ]]; then
    echo $[2]
  fi
done

Drag options to blanks, or click blank then click option'

A>

B"$fruit"

C<

Decho

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' would print fruits with names shorter than 5 letters.

Printing 'echo' instead of the variable name.

Use '>' to check if length is greater than 5, and print the fruit variable.

5fill in blank

hard

Fill all three blanks to create a loop that prints fruits in uppercase only if their name length is less than 7.

Bash Scripting

for fruit in apple banana cherry date; do
  if [[ ${#fruit} [1] 7 ]]; then
    [2] "$fruit" | [3] '[:lower:]' '[:upper:]'
  fi
done

Drag options to blanks, or click blank then click option'

A<

Becho

Ctr

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' instead of '<' for the length check.

Using 'cut' or other commands instead of 'tr' for case conversion.

Use '<' to check length less than 7, 'echo' to output the fruit, and 'tr' to convert to uppercase.

Practice

1. What does the following Bash code do?

for item in apple banana cherry; do echo $item; done

easy

A. Prints each fruit name on a new line

B. Prints all fruit names on the same line

C. Creates a list of fruits without printing

D. Causes a syntax error

Solution

1. Step 1: Understand the for loop structure

   The loop goes through each word in the list: apple, banana, cherry.

2. Step 2: Check the command inside the loop

   It prints each item using echo, so each fruit name appears on its own line.

3. Final Answer:

   Prints each fruit name on a new line -> Option A

4. Quick Check:

   Loop prints each item line by line = C [OK]

Hint: For loops print each list item one by one [OK]

Common Mistakes:

• Thinking echo prints all items on one line
• Confusing list iteration with variable assignment
• Missing the do/done keywords

2. Which of these is the correct syntax for a Bash for loop over a list of words?

easy

A. loop item in apple banana cherry: echo $item

B. for (item in apple banana cherry) { echo $item }

C. for item in apple banana cherry; do echo $item; done

D. foreach item in apple banana cherry; echo $item; end

Solution

1. Step 1: Identify valid Bash for loop syntax

   Bash uses: for variable in list; do commands; done

2. Step 2: Compare options

   Only for item in apple banana cherry; do echo $item; done matches Bash syntax exactly; others use syntax from other languages or invalid forms.

3. Final Answer:

   for item in apple banana cherry; do echo $item; done -> Option C

4. Quick Check:

   Bash for loop syntax = D [OK]

Hint: Bash loops use 'for var in list; do ...; done' [OK]

Common Mistakes:

• Using parentheses or braces like other languages
• Using foreach or loop keywords not in Bash
• Omitting do or done keywords

3. What is the output of this script?

for word in one two three; do echo "$word"; done

medium

A. one
two
three (each on its own line)

B. one\ntwo\nthree

C. one
two
three

D. one two three

Solution

1. Step 1: Understand the loop iteration

   The loop runs three times, each time echoing one word: one, two, three.

2. Step 2: Understand echo output with quotes

   Quotes preserve spaces but echo prints each word on a new line by default.

3. Final Answer:

   one two three (each on its own line) -> Option A

4. Quick Check:

   Echo prints each item on separate lines = A [OK]

Hint: Echo prints each loop item on its own line by default [OK]

Common Mistakes:

• Thinking echo prints all items on one line
• Confusing literal \n with newline
• Ignoring quotes effect on output

4. Find the error in this Bash script:

for item apple banana cherry; do echo $item; done

medium

A. Missing semicolon after 'banana'

B. Variable name 'item' is invalid

C. Incorrect use of quotes around list items

D. Missing 'in' keyword after 'for item'

Solution

1. Step 1: Check for loop syntax

   Bash requires 'for variable in list; do ...; done'. The 'in' keyword is missing here.

2. Step 2: Identify the error cause

   Without 'in', Bash cannot parse the list, causing a syntax error.

3. Final Answer:

   Missing 'in' keyword after 'for item' -> Option D

4. Quick Check:

   For loop needs 'in' keyword = B [OK]

Hint: Always include 'in' after variable in for loops [OK]

Common Mistakes:

• Forgetting the 'in' keyword
• Adding unnecessary semicolons inside list
• Misnaming variables with invalid characters

5. You want to print only the fruits that start with the letter 'b' from this list:

fruits="apple banana cherry blueberry"
for fruit in $fruits; do
  # Fill condition here
  echo "$fruit"
done

Which condition inside the loop correctly filters fruits starting with 'b'?

hard

A. if [ $fruit = 'b' ]; then

B. if [[ $fruit == b* ]]; then

C. if [[ $fruit =~ b* ]]; then

D. if [ $fruit == 'b*' ]; then

Solution

1. Step 1: Understand string pattern matching in Bash

   Double brackets [[ ]] support pattern matching with == and wildcards like '*'.

2. Step 2: Check each condition

   A uses [[ $fruit == b* ]] which matches strings starting with 'b'. B uses single brackets for exact 'b' match. C uses [[ $fruit =~ b* ]]; b* regex matches zero or more 'b's (including none), so every string. D uses single brackets which don't support patterns or ==.

3. Final Answer:

   if [[ $fruit == b* ]]; then -> Option B

4. Quick Check:

   Use [[ var == pattern* ]] for prefix match = A [OK]

Hint: Use [[ var == prefix* ]] to match string start in Bash [OK]

Common Mistakes:

• Using single brackets with wildcard patterns
• Confusing regex =~ with == operator
• Comparing to exact string 'b' instead of prefix