Adding and removing elements in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output after adding an element to an array?

Consider the following Bash script that adds an element to an array. What will be the output?

Bash Scripting

arr=(apple banana cherry)
arr+=(date)
echo "${arr[@]}"

A apple banana cherry date

B apple banana cherry

C apple banana cherry date date

D date

💡 Hint

Remember that += adds elements to the end of the array.

The += operator appends the new element 'date' to the existing array. So the array contains all four fruits.

💻 Command Output

intermediate

What happens when you remove an element from an array by index?

Given this Bash script, what will be the output?

Bash Scripting

arr=(red green blue yellow)
unset arr[1]
echo "${arr[0]} ${arr[1]} ${arr[2]} ${arr[3]}"

A red blue yellow

B red green blue yellow

C red green yellow

D red blue yellow

💡 Hint

unset removes the element but does not reindex the array.

The element at index 1 ('green') is removed, but the array keeps its indices, so echo prints a blank space where the removed element was.

📝 Syntax

advanced

Which option correctly removes the first element from a Bash array?

You want to remove the first element from the array 'arr'. Which command does this correctly?

Bash Scripting

arr=(one two three four)

A arr=(${arr[1:]})

B arr=(${arr[@]} - 1)

C arr=(${arr[@]:1})

D unset arr[0]

💡 Hint

Use array slicing to skip the first element.

Option C uses slicing to create a new array starting from index 1, effectively removing the first element.

🔧 Debug

advanced

Why does this script fail to remove an element correctly?

Look at this script and find why it does not remove the element 'orange' from the array.

Bash Scripting

fruits=(apple orange banana)
for i in "${!fruits[@]}"; do
  if [[ "${fruits[i]}" == "orange" ]]; then
    unset fruits[$i]
  fi
done
echo "${fruits[0]} ${fruits[1]} ${fruits[2]}"

A The unset command should use ${fruits[i]} instead of fruits[i]

B The array is not reindexed after unset, so the output has a blank space

C The loop variable i is quoted, causing it to be a string instead of an index

D The if condition syntax is incorrect

💡 Hint

unset removes the element but does not shift the array indices.

unset removes the element but leaves a gap in the array indices, so the output shows a blank space where 'orange' was.

🚀 Application

expert

How to add multiple elements to a Bash array in one command?

You have an array: arr=(cat dog). You want to add 'bird' and 'fish' at once. Which command does this correctly?

A arr+=(bird fish)

B arr+=('bird fish')

C arr=(${arr[@]} bird fish)

D arr=(${arr} bird fish)

💡 Hint

Use += with parentheses to add multiple elements as separate items.

Option A appends two separate elements 'bird' and 'fish' to the array correctly.