wc (word, line, character count) in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of wc with multiple files

What is the output of the following command if file1.txt contains 3 lines, 10 words, and 50 characters, and file2.txt contains 2 lines, 5 words, and 20 characters?

wc file1.txt file2.txt

Linux CLI

wc file1.txt file2.txt

A

 3 10 50 file1.txt
 2 5 20 file2.txt
 6 15 70 total

B

 3 10 50 file1.txt
 2 5 20 file2.txt
 5 15 70 total

C

 3 10 50 file1.txt
 2 5 20 file2.txt
 5 15 60 total

D

 3 10 50 file1.txt
 2 5 20 file2.txt
 5 15 70 file2.txt

💡 Hint

Remember that wc sums lines, words, and characters for the total line.

The wc command outputs lines, words, and characters for each file, then sums them for the total line. Here, 3+2=5 lines, 10+5=15 words, 50+20=70 characters.

💻 Command Output

intermediate

Counting words only with wc

What is the output of this command if input.txt contains the text "Hello world from Linux CLI"?

wc -w input.txt

Linux CLI

wc -w input.txt

A 4 input.txt

B 6 input.txt

C Error: file not found

D 5 input.txt

💡 Hint

Count the words separated by spaces.

The text has 5 words: Hello, world, from, Linux, CLI. The -w option counts words only.

📝 Syntax

advanced

Correct usage of wc to count lines

Which option correctly counts only the number of lines in file.txt?

A wc -l file.txt

B wc -c file.txt

C wc -w file.txt

D wc --lines file.txt

💡 Hint

The option for lines is a single letter.

The -l option counts lines. -c counts bytes, -w counts words, and --lines is not a valid option.

🔧 Debug

advanced

Identify the error in wc command usage

What error will this command produce?

wc -x file.txt

Linux CLI

wc -x file.txt

A

wc: invalid option -- 'x'
Try 'wc --help' for more information.

B 0 file.txt

C Counts lines, words, and bytes normally

D wc: file.txt: No such file or directory

💡 Hint

Check if -x is a valid wc option.

The -x option is not valid for wc, so it produces an invalid option error.

🚀 Application

expert

Using wc in a script to count total words in multiple files

You want to write a script that sums the total number of words across three files: a.txt, b.txt, and c.txt. Which command will correctly output only the total word count?

A wc -w a.txt b.txt c.txt | grep total | awk '{print $2}'

B wc -w a.txt b.txt c.txt | head -1 | awk '{print $1}'

C wc -w a.txt b.txt c.txt | tail -1 | awk '{print $1}'

D wc -w a.txt b.txt c.txt | awk '{sum += $1} END {print sum}'

💡 Hint

The total line is the last line of wc output when multiple files are given.

When wc -w is run on multiple files, the last line shows the total word count. tail -1 gets that line, and awk '{print $1}' extracts the count.