tr (translate characters) in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this tr command?

Given the input string hello world, what is the output of the command echo 'hello world' | tr 'a-z' 'A-Z'?

Linux CLI

echo 'hello world' | tr 'a-z' 'A-Z'

A hello world

B HELLO WORLD

C HELLO world

D Error: invalid range

💡 Hint

The tr command can convert lowercase letters to uppercase by specifying ranges.

The command translates all lowercase letters (a-z) to their uppercase equivalents (A-Z), so 'hello world' becomes 'HELLO WORLD'.

💻 Command Output

intermediate

What does this tr command output?

What is the output of echo '123-456-7890' | tr -d '-'?

Linux CLI

echo '123-456-7890' | tr -d '-'

A 1234567890

B 123 456 7890

C Error: invalid option

D 123-456-7890

💡 Hint

The -d option deletes characters specified in the set.

The command deletes all dashes '-' from the input, resulting in '1234567890'.

💻 Command Output

advanced

What is the output of this tr command with squeeze?

Given the input echo 'aaabbbcccaaa' | tr -s 'a', what is the output?

Linux CLI

echo 'aaabbbcccaaa' | tr -s 'a'

A abbbccc

B abbbcccaa

C abbbccca

D Error: invalid option

💡 Hint

The -s option squeezes repeated characters in the set into one.

The command squeezes repeated 'a's into a single 'a', so 'aaabbbcccaaa' becomes 'abbbccca'.

💻 Command Output

advanced

What error does this tr command produce?

What error message results from running echo 'test' | tr 'a-z' 'A-Z' '0-9'?

Linux CLI

echo 'test' | tr 'a-z' 'A-Z' '0-9'

A tr: extra operand '0-9'

B test

C TEST

D Error: invalid range

💡 Hint

The tr command accepts only two sets of characters for translation.

The command provides three arguments to tr, which expects only two sets. This causes an error about an extra operand.

🚀 Application

expert

How many characters are in the output after this tr command?

Given the input string echo 'aabbccddeeff' | tr -d 'bdf', how many characters does the output contain?

Linux CLI

echo 'aabbccddeeff' | tr -d 'bdf'

A 8

B 9

C 12

D 6

💡 Hint

Count the characters after deleting all 'b', 'd', and 'f'.

The input has 12 characters: a a b b c c d d e e f f. Deleting 'b', 'd', and 'f' removes 2 b's, 2 d's, and 2 f's (6 total). Remaining characters: a a c c e e (6 characters). So output length is 6.