Uppercase and lowercase conversion in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this Bash command?

Consider the following command that converts a string to uppercase. What will it output?

Bash Scripting

echo "hello World" | tr '[:lower:]' '[:upper:]'

A hello World

B HELLO WORLD

C Hello World

D HELLO world

💡 Hint

The tr command replaces characters from one set to another.

The tr command with '[:lower:]' and '[:upper:]' converts all lowercase letters to uppercase. So 'hello World' becomes 'HELLO WORLD'.

💻 Command Output

intermediate

What is the output of this Bash command?

What will this command output when converting a string to lowercase?

Bash Scripting

echo "BASH SCRIPTING" | tr '[:upper:]' '[:lower:]'

A bash scripting

B BASH SCRIPTING

C Bash Scripting

D bash SCRIPTING

💡 Hint

The tr command changes uppercase letters to lowercase letters.

The tr command replaces all uppercase letters with lowercase letters, so 'BASH SCRIPTING' becomes 'bash scripting'.

📝 Syntax

advanced

Which option correctly converts a variable to uppercase in Bash?

Given a variable name VAR="hello", which command correctly converts its value to uppercase?

Bash Scripting

VAR="hello"

A echo ${VAR^^:}

B echo ${VAR^^^}

C echo ${VAR^^?}

D echo ${VAR^^}

💡 Hint

Use Bash parameter expansion for case conversion.

In Bash 4+, ${VAR^^} converts all characters in VAR to uppercase. Other options are invalid syntax.

💻 Command Output

advanced

What is the output of this Bash script snippet?

What will this script output?

Bash Scripting

input="HeLLo WoRLd"
echo "$input" | awk '{print tolower($0)}'

A hello world

B HeLLo WoRLd (unchanged)

C HELLO WORLD

D HeLLo WoRLd

💡 Hint

awk's tolower function converts text to lowercase.

The awk command with tolower converts the entire input string to lowercase, so output is 'hello world'.

🚀 Application

expert

How many lines will be printed by this script?

This script reads lines from a file and prints only those lines that are uppercase. How many lines will it print?

Bash Scripting

while IFS= read -r line; do
  if [[ "$line" == "${line^^}" ]]; then
    echo "$line"
  fi
done < input.txt

A No lines will be printed

B All lines regardless of case

C Only lines that are fully uppercase

D Only lines that are fully lowercase

💡 Hint

The condition compares the line to its uppercase version.

The script prints lines where the original line equals its uppercase version, meaning the line is fully uppercase.