wc (word, line, character count) in Linux CLI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to count the number of lines in a file named 'file.txt'.

Linux CLI

wc [1] file.txt

Drag options to blanks, or click blank then click option'

A-w

B-l

C-c

D-m

Attempts:

3 left

💡 Hint

Common Mistakes

Using -w or -c instead of -l will count words or bytes, not lines.

The -l option tells wc to count lines in the file.

2fill in blank

medium

Complete the code to count the number of words in 'document.txt'.

Linux CLI

wc [1] document.txt

Drag options to blanks, or click blank then click option'

A-w

B-l

C-m

D-c

Attempts:

3 left

💡 Hint

Common Mistakes

Using -l counts lines, not words.

Using -c or -m counts bytes or characters.

The -w option counts the words in the file.

3fill in blank

hard

Fix the error in the command to count characters in 'notes.txt'.

Linux CLI

wc [1] notes.txt

Drag options to blanks, or click blank then click option'

A-w

B-l

C-m

D-c

Attempts:

3 left

💡 Hint

Common Mistakes

Using -c counts bytes, which can be different from characters.

The -m option counts characters (not bytes). Using -c counts bytes, which may differ if file has multibyte characters.

4fill in blank

hard

Fill both blanks to count lines and words in 'story.txt'.

Linux CLI

wc [1] [2] story.txt

Drag options to blanks, or click blank then click option'

A-l

B-w

C-c

D-m

Attempts:

3 left

💡 Hint

Common Mistakes

Using -c or -m instead of -w for word count.

Mixing up line and character options.

Use -l for lines and -w for words. Both options can be combined.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps each filename to its word count, only if the word count is greater than 100.

Linux CLI

result = [1]: [2] for [3] in files if [2] > 100}}

Drag options to blanks, or click blank then click option'

Afile

Bwc -w file

Dfilename

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong variable names.

Not filtering word counts correctly.

This comprehension maps each file to its word count using wc -w file, filtering counts greater than 100.

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