cat (display file contents) in Linux CLI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to display the contents of a file named notes.txt.

Linux CLI

cat [1]

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

A-l

Becho

Cls

Dnotes.txt

Attempts:

3 left

💡 Hint

Common Mistakes

Using ls instead of the file name after cat.

Adding options like -l which cat does not use.

The cat command followed by the filename notes.txt displays the file's contents.

2fill in blank

medium

Complete the command to display the contents of two files, file1.txt and file2.txt, one after the other.

Linux CLI

cat [1]

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

A-a file1.txt file2.txt

Bfile1.txt file2.txt

Cfile1.txt,file2.txt

D-l file1.txt file2.txt

Attempts:

3 left

💡 Hint

Common Mistakes

Using commas between file names instead of spaces.

Adding unsupported options like -a or -l.

Listing the two filenames separated by a space after cat displays their contents in order.

3fill in blank

hard

Fix the error in the command to display the contents of report.txt.

Linux CLI

cat [1]

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

Areport.txt

B-r report.txt

Creport.txt -r

Dreporttxt

Attempts:

3 left

💡 Hint

Common Mistakes

Adding unsupported options like -r.

Misspelling the filename.

The correct command is cat report.txt. Options like -r are invalid for cat, and misspelled filenames cause errors.

4fill in blank

hard

Fill both blanks to create a command that shows the contents of log1.txt in reverse order using tac.

Linux CLI

[1] [2]

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

Atac

Bcat

Clog2.txt

Dlog1.txt

Attempts:

3 left

💡 Hint

Common Mistakes

Using cat instead of tac for reverse display.

Swapping the filenames or commands.

The command tac log1.txt displays the contents of log1.txt in reverse order. Here, tac is the reverse of cat.

5fill in blank

hard

Fill all four blanks to create a command that concatenates part1.txt and part2.txt and saves the result to full.txt.

Linux CLI

[1] [2] [3] > [4]

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

Acat

Bpart1.txt

Cfull.txt

Dpart2.txt

Attempts:

3 left

💡 Hint

Common Mistakes

Using only one input file.

Redirecting output to an input file.

Swapping input and output files.

The command cat part1.txt part2.txt > full.txt joins the two files and writes the output to full.txt.

Practice

1. What does the cat command do in Linux?

easy

A. Deletes a file permanently

B. Displays the contents of a file on the terminal

C. Changes file permissions

D. Creates a new directory

Solution

1. Step 1: Understand the purpose of cat

   The cat command is used to read and display the contents of files in the terminal.

2. Step 2: Compare with other options

   Deleting files, changing permissions, or creating directories are done by other commands like rm, chmod, and mkdir.

3. Final Answer:

   Displays the contents of a file on the terminal -> Option B

4. Quick Check:

   cat shows file contents [OK]

Hint: Remember: cat = concatenate and show file content [OK]

Common Mistakes:

• Confusing cat with rm or mkdir
• Thinking cat edits files
• Assuming cat deletes files

2. Which of the following is the correct syntax to display the contents of a file named notes.txt using cat?

easy

A. cat notes.txt

B. cat -f notes.txt

C. cat > notes.txt

D. cat -r notes.txt

Solution

1. Step 1: Identify the basic syntax of cat

   The basic command to display a file is cat filename, so cat notes.txt is correct.

2. Step 2: Understand incorrect options

   -f and -r are not valid options for cat. The cat > filename syntax is used to create or overwrite a file, not display it.

3. Final Answer:

   cat notes.txt -> Option A

4. Quick Check:

   Basic syntax is cat filename [OK]

Hint: Use just 'cat filename' to show file content [OK]

Common Mistakes:

• Adding invalid options like -f or -r
• Using > which overwrites files
• Confusing cat with other commands

3. What will be the output of the command cat -n file.txt if file.txt contains:

Hello
World

medium

A. Hello
World

B. Hello 1
World 2

C. Error: invalid option

D. 1 Hello
2 World

Solution

1. Step 1: Understand the -n option

   The -n option numbers each line of the output when displaying file contents.

2. Step 2: Apply numbering to each line

   Given the file has two lines: "Hello" and "World", the output will prefix each line with its line number: "1 Hello" and "2 World".

3. Final Answer:

   1 Hello 2 World -> Option D

4. Quick Check:

   cat -n adds line numbers [OK]

Hint: Use -n to add line numbers to output [OK]

Common Mistakes:

• Ignoring line numbers
• Placing numbers after text
• Thinking -n is invalid

4. You run cat file1.txt file2.txt but get an error: cat: file2.txt: No such file or directory. What is the most likely cause?

medium

A. You used the wrong command syntax

B. file1.txt is empty

C. file2.txt does not exist in the current directory

D. You do not have permission to read file1.txt

Solution

1. Step 1: Analyze the error message

   The error says file2.txt is missing, so the system cannot find it in the current directory.

2. Step 2: Check other options

   Empty file1.txt or permission issues on file1.txt would not cause this error. The syntax is correct for displaying multiple files.

3. Final Answer:

   file2.txt does not exist in the current directory -> Option C

4. Quick Check:

   Missing file causes 'No such file' error [OK]

Hint: Check file existence if 'No such file' error appears [OK]

Common Mistakes:

• Assuming syntax error
• Ignoring missing file
• Blaming permissions wrongly

5. You want to combine the contents of chapter1.txt and chapter2.txt into a new file book.txt. Which command correctly does this using cat?

hard

A. cat chapter1.txt chapter2.txt > book.txt

B. cat > chapter1.txt chapter2.txt > book.txt

C. cat chapter1.txt > chapter2.txt > book.txt

D. cat book.txt > chapter1.txt chapter2.txt

Solution

1. Step 1: Understand output redirection with cat

   The command cat file1 file2 > newfile concatenates file1 and file2 contents and writes to newfile.

2. Step 2: Analyze each option

   cat chapter1.txt chapter2.txt > book.txt correctly concatenates chapter1.txt and chapter2.txt into book.txt. Options A, C, and D misuse redirection or file order, causing errors or overwrites.

3. Final Answer:

   cat chapter1.txt chapter2.txt > book.txt -> Option A

4. Quick Check:

   Use cat file1 file2 > newfile to combine files [OK]

Hint: Use > after files to save combined output [OK]

Common Mistakes:

• Misplacing > causing overwrite
• Using > multiple times incorrectly
• Confusing input and output files