tr for character transformation in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of tr command with character deletion

What is the output of this command?

echo "hello world" | tr -d 'aeiou'

Bash Scripting

echo "hello world" | tr -d 'aeiou'

A hll wrld

B hello world

C h e l l o w o r l d

D Syntax error

💡 Hint

The -d option deletes characters specified.

The command deletes all vowels from the input string, leaving only consonants and spaces.

💻 Command Output

intermediate

Transform lowercase to uppercase using tr

What is the output of this command?

echo "bash scripting" | tr 'a-z' 'A-Z'

Bash Scripting

echo "bash scripting" | tr 'a-z' 'A-Z'

A BASH SCRIPTING

B bash scripting

C Bash Scripting

D Syntax error

💡 Hint

tr replaces characters from the first set with the second set.

All lowercase letters are converted to uppercase letters.

💻 Command Output

advanced

Output of tr with complement and squeeze

What is the output of this command?

echo "aaabbbccc111222333" | tr -cs 'a-z' $'\n'

Bash Scripting

echo "aaabbbccc111222333" | tr -cs 'a-z' $'\n'

A aaa bbb ccc

B

aaa
bbb
ccc

C aaabbbccc

D Syntax error

💡 Hint

The -c option complements the set; -s squeezes repeated characters.

The command replaces all characters except lowercase letters with newlines and squeezes repeats, resulting in each group of letters on a new line.

💻 Command Output

advanced

Effect of tr with overlapping sets

What is the output of this command?

echo "123abc" | tr '1-3a-c' 'x-z1-3'

Bash Scripting

echo "123abc" | tr '1-3a-c' 'x-z1-3'

A 123abc

B Syntax error

C xyz123

D xxx111

💡 Hint

Characters in the first set are replaced by corresponding characters in the second set.

Digits 1-3 map to x-z and letters a-c map to 1-3, so '123abc' becomes 'xyz123'.

💻 Command Output

expert

Count unique characters after tr transformation

What is the number of unique characters in the output of this command?

echo "Hello World! 123" | tr 'A-Za-z' 'n-za-mN-ZA-M' | tr -d ' ' | tr -d '!' | fold -w1 | sort -u | wc -l

Bash Scripting

echo "Hello World! 123" | tr 'A-Za-z' 'n-za-mN-ZA-M' | tr -d ' ' | tr -d '!' | fold -w1 | sort -u | wc -l

A 12

B 15

C 13

D 10

💡 Hint

The first tr applies ROT13 cipher, then spaces and '!' are removed, unique characters counted.

ROT13 transforms letters, digits remain unchanged. After removing spaces and '!', counting unique characters yields 10.