wc (word, line, character count) in Linux CLI - Mini Project: Build & Apply

Counting Words, Lines, and Characters with wc

📖 Scenario: You are working on a small project where you need to analyze text files to find out how many lines, words, and characters they contain. This is useful when checking reports, logs, or any text data.

🎯 Goal: Learn how to use the wc command to count lines, words, and characters in a text file.

📋 What You'll Learn

Create a text file named sample.txt with specific content.

Use a variable to store the filename.

Use the wc command with options to count lines, words, and characters.

Display the output clearly.

💡 Why This Matters

🌍 Real World

Counting lines, words, and characters is common when checking text files like logs, reports, or code files to understand their size or content quickly.

💼 Career

Many IT and scripting jobs require using command-line tools like wc to automate text processing and reporting tasks efficiently.

1

Create the text file sample.txt

Create a text file named sample.txt with exactly these three lines of text:
Hello world
This is a test file
Counting words and lines

Linux CLI

# Use a text editor or echo commands to create sample.txt
# Your code here

Hint

Use echo with redirection > and >> to create and add lines to the file.

2

Store the filename in a variable

Create a variable called filename and set it to the string sample.txt.

Linux CLI

echo "Hello world" > sample.txt
echo "This is a test file" >> sample.txt
echo "Counting words and lines" >> sample.txt

# Create a variable filename with value sample.txt
# Your code here

Hint

Use filename="sample.txt" to assign the filename.

3

Use wc to count lines, words, and characters

Use the wc command with options -l, -w, and -m on the file stored in the variable filename. Store the output in a variable called result.

Linux CLI

echo "Hello world" > sample.txt
echo "This is a test file" >> sample.txt
echo "Counting words and lines" >> sample.txt

filename="sample.txt"

# Use wc with -l -w -m options on $filename and store in result
# Your code here

Hint

Use command substitution with $( ) to save the output.

4

Display the counting result

Print the content of the variable result to show the lines, words, and characters count of sample.txt.

Linux CLI

echo "Hello world" > sample.txt
echo "This is a test file" >> sample.txt
echo "Counting words and lines" >> sample.txt

filename="sample.txt"

result=$(wc -l -w -m "$filename")

# Print the result variable
# Your code here

Hint

Use echo "$result" to print the output.

Practice

1. What does the wc command do in Linux?

easy

A. Counts lines, words, and characters in text

B. Changes file permissions

C. Lists files in a directory

D. Displays disk usage

Solution

1. Step 1: Understand the purpose of wc

   The wc command is used to count lines, words, and characters in text files or input.

2. Step 2: Compare with other commands

   Other options like changing permissions or listing files are done by different commands (chmod, ls), not wc.

3. Final Answer:

   Counts lines, words, and characters in text -> Option A

4. Quick Check:

   wc = counts lines, words, characters [OK]

Hint: Remember: wc = word count tool for text [OK]

Common Mistakes:

• Confusing wc with ls or chmod
• Thinking wc changes files
• Assuming wc shows disk usage

2. Which of the following is the correct syntax to count only the number of lines in a file named file.txt?

easy

A. wc -w file.txt

B. wc -l file.txt

C. wc -c file.txt

D. wc -m file.txt

Solution

1. Step 1: Identify option for line count

   The -l option with wc counts lines in the file.

2. Step 2: Verify other options

   -w counts words, -c counts bytes, and -m counts characters, so they are incorrect for line count.

3. Final Answer:

   wc -l file.txt -> Option B

4. Quick Check:

   -l means lines [OK]

Hint: Use -l to count lines, not -w or -c [OK]

Common Mistakes:

• Using -w or -c instead of -l
• Forgetting the filename
• Mixing up -m and -c options

3. Given a file example.txt containing the text:

Hello world
This is a test

What is the output of wc example.txt?

medium

A. 2 6 27 example.txt

B. 3 5 24 example.txt

C. 2 5 24 example.txt

D. 3 6 25 example.txt

Solution

1. Step 1: Count lines, words, and characters in the file

   Lines: 2 ("Hello world" and "This is a test")
   Words: 6 ("Hello", "world", "This", "is", "a", "test")
   Characters: Count all characters including spaces and newlines.
   "Hello world" = 11 chars, newline = 1, "This is a test" = 14 chars, newline = 1, total = 27 chars.

2. Step 2: Match counts with options

   2 6 27 example.txt matches exactly: 2 lines, 6 words, 27 characters.

3. Final Answer:

   2 6 27 example.txt -> Option A

4. Quick Check:

   Lines=2, Words=6, Characters=27 [OK]

Hint: Count lines, words, chars carefully; wc shows all three by default [OK]

Common Mistakes:

• Miscounting words or lines
• Ignoring newline characters in count
• Assuming output order is different

4. You run wc -l file.txt but get an error: wc: invalid option -- 'x'. What is the likely cause?

medium

A. The file file.txt does not exist

B. You forgot to specify the filename

C. You typed an invalid option like -x by mistake

D. The wc command is not installed

Solution

1. Step 1: Analyze the error message

   The error says "invalid option -- 'x'", meaning wc received an option -x which it does not recognize.

2. Step 2: Identify common causes

   This usually happens if you mistype an option, for example -x instead of -l or -w.

3. Final Answer:

   You typed an invalid option like -x by mistake -> Option C

4. Quick Check:

   Invalid option error means wrong flag [OK]

Hint: Check option spelling carefully if wc shows invalid option error [OK]

Common Mistakes:

• Confusing file not found with invalid option error
• Assuming missing filename causes invalid option error
• Ignoring typo in command options

5. You want to count only the characters (not bytes) in a UTF-8 encoded file data.txt. Which command should you use?

hard

A. wc -c data.txt

B. wc -w data.txt

C. wc -l data.txt

D. wc -m data.txt

Solution

1. Step 1: Understand difference between -c and -m

   -c counts bytes, which may differ from characters in UTF-8 files because some characters use multiple bytes.
   -m counts characters, correctly handling multibyte UTF-8 characters.

2. Step 2: Choose correct option for character count

   To count characters (not bytes), use wc -m.

3. Final Answer:

   wc -m data.txt -> Option D

4. Quick Check:

   -m counts characters, not bytes [OK]

Hint: Use -m for characters, -c counts bytes (important for UTF-8) [OK]

Common Mistakes:

• Using -c and expecting character count
• Confusing words (-w) with characters
• Ignoring UTF-8 multibyte character effects