Unsetting variables (unset) in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output after unsetting a variable?

Consider the following Bash script snippet:

var="Hello"
unset var
echo "$var"

What will be the output when this script runs?

Bash Scripting

var="Hello"
unset var
echo "$var"

A (no output — empty line)

B Hello

C unset: var: not found

D Error: variable var is unset

💡 Hint

After unsetting, the variable no longer exists.

The unset command removes the variable from the environment. Echoing an unset variable produces an empty line.

💻 Command Output

intermediate

What happens when unsetting an array element?

Given this Bash code:

arr=(one two three)
unset arr[1]
echo "${arr[@]}"

What is the output?

Bash Scripting

arr=(one two three)
unset arr[1]
echo "${arr[@]}"

A one three

B one two three

C one three

D Error: cannot unset array element

💡 Hint

Unsetting an array element removes it, shifting does not happen.

Unsetting arr[1] removes the second element 'two'. The remaining elements are 'one' and 'three'.

📝 Syntax

advanced

Which option correctly unsets multiple variables in one command?

Select the correct Bash command to unset variables var1, var2, and var3 at once.

A unset [var1 var2 var3]

B unset(var1, var2, var3)

C unset var1; var2; var3

D unset var1 var2 var3

💡 Hint

The unset command accepts multiple variable names separated by spaces.

Option D uses the correct syntax: 'unset' followed by variable names separated by spaces.

🔧 Debug

advanced

Why does this unset command fail?

Given this script snippet:

myvar="data"
unset "$myvar"
echo "$myvar"

Why does the variable still print 'data' after unsetting?

A Because unset cannot unset variables with quotes

B Because unset "$myvar" tries to unset a variable named 'data', not 'myvar'

C Because unset only works on environment variables

D Because unset requires the variable name without $ sign

💡 Hint

Check what the argument to unset actually is.

Using quotes causes the variable's value to be passed to unset, so it tries to unset a variable named 'data', which does not exist.

🚀 Application

expert

How many variables remain after this script runs?

Consider this Bash script:

var1=10
var2=20
var3=30
unset var2
var4=40
unset var5

How many variables named var1, var2, var3, var4, var5 exist after running?

A 3 variables: var1, var3, var4

B 4 variables: var1, var3, var4, var5

C 5 variables: var1, var2, var3, var4, var5

D 2 variables: var1, var3

💡 Hint

Unset removes variables if they exist; unsetting a non-existent variable does nothing.

var2 is unset, var5 was never set, so only var1, var3, and var4 remain.