First Linux commands in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of the ls command?

You run the ls command in a directory containing three files: file1.txt, file2.txt, and script.sh. What will the command output?

Linux CLI

ls

A

file1.txt
file2.txt
script.sh

B No output

C file1.txt,file2.txt,script.sh

D file1.txt file2.txt script.sh

💡 Hint

The ls command lists files separated by spaces in multi-column format by default.

The ls command outputs the file names separated by spaces on a single line by default (for short names that fit), so the output will be file1.txt file2.txt script.sh.

💻 Command Output

intermediate

What does the pwd command output?

You are currently inside the directory /home/user/documents. What will the pwd command output?

Linux CLI

pwd

A /home/user/documents

B documents

C user/documents

D /home/user

💡 Hint

The pwd command shows the full path of the current directory.

The pwd command prints the full absolute path of the current working directory, which is /home/user/documents.

💻 Command Output

advanced

What is the output of the echo $HOME command?

Assuming your home directory is /home/alex, what will the command echo $HOME output?

Linux CLI

echo $HOME

A $HOME

B home/alex

C /home/alex

D Error: variable not found

💡 Hint

The $HOME variable stores the path to your home directory.

The shell replaces $HOME with the path of the home directory, so the output is /home/alex.

💻 Command Output

advanced

What error does this command produce?

You run the command cd /nonexistentfolder. What error message will you see?

Linux CLI

cd /nonexistentfolder

A bash: cd: /nonexistentfolder: No such file or directory

B cd: command not found

C Permission denied

D No output, command succeeds

💡 Hint

The folder does not exist, so cd cannot change to it.

The shell reports that the directory does not exist with the message: bash: cd: /nonexistentfolder: No such file or directory.

💻 Command Output

expert

How many files are listed by this command?

You run ls -l | grep '^-' | wc -l in a directory. What does this command count?

Linux CLI

ls -l | grep '^-' | wc -l

A The number of directories in the directory

B The number of regular files in the directory

C The total number of files and directories

D The number of symbolic links

💡 Hint

The ls -l output starts lines with - for files and d for directories.

The command lists files in long format, filters lines starting with - (regular files), then counts those lines. So it counts regular files only.

Practice

1. Which Linux command shows the current directory you are in?

easy

A. pwd

B. ls

C. cd

D. mkdir

Solution

1. Step 1: Understand the purpose of pwd

   The pwd command stands for "print working directory" and shows the current folder path.

2. Step 2: Compare with other commands

   ls lists files, cd changes directory, and mkdir creates a folder, so they don't show the current directory.

3. Final Answer:

   pwd -> Option A

4. Quick Check:

   Current directory command = pwd [OK]

Hint: Remember: pwd = print working directory [OK]

Common Mistakes:

• Confusing ls with pwd
• Using cd to show directory
• Thinking mkdir shows current folder

2. Which of the following is the correct syntax to create a new directory named projects?

easy

A. mkdir projects

B. mk projects

C. create projects

D. newdir projects

Solution

1. Step 1: Identify the command to create directories

   The standard Linux command to make a directory is mkdir.

2. Step 2: Check the syntax

   The correct syntax is mkdir directory_name, so mkdir projects is correct.

3. Final Answer:

   mkdir projects -> Option A

4. Quick Check:

   Create directory command = mkdir [OK]

Hint: mkdir means make directory; use it to create folders [OK]

Common Mistakes:

• Using mk instead of mkdir
• Typing create instead of mkdir
• Using newdir which is not a command

3. What will be the output of the following commands?

mkdir testdir
cd testdir
pwd

medium

A. /testdir

B. /home/testdir

C. /home/username/testdir

D. testdir

Solution

1. Step 1: Understand the commands

   mkdir testdir creates a folder named testdir. cd testdir moves into that folder. pwd prints the full path of the current directory.

2. Step 2: Determine the full path

   Assuming the user starts in their home directory (like /home/username), after changing into testdir, pwd will show /home/username/testdir.

3. Final Answer:

   /home/username/testdir -> Option C

4. Quick Check:

   pwd after cd into testdir = full path /home/username/testdir [OK]

Hint: pwd shows full path, not just folder name [OK]

Common Mistakes:

• Expecting just folder name output
• Assuming root directory path
• Confusing relative and absolute paths

4. You run the command cd myfolder but get an error: bash: cd: myfolder: No such file or directory. What is the most likely cause?

medium

A. You do not have permission to use cd

B. The folder myfolder does not exist in the current directory

C. The cd command is misspelled

D. You need to use mkdir before cd

Solution

1. Step 1: Analyze the error message

   The error says "No such file or directory", meaning the folder named myfolder is not found in the current location.

2. Step 2: Check other options

   cd is a basic command and usually not misspelled here. Permissions errors give different messages. mkdir creates folders but is not required before cd if the folder exists.

3. Final Answer:

   The folder myfolder does not exist in the current directory -> Option B

4. Quick Check:

   cd error means folder missing [OK]

Hint: Check folder exists before cd [OK]

Common Mistakes:

• Assuming permission error
• Thinking cd needs mkdir first
• Misspelling cd command

5. You want to create a new folder named backup inside your current directory and then move into it. Which sequence of commands will do this correctly?

hard

A. mkdir
cd backup

B. cd backup
mkdir backup

C. cd backup
cd backup

D. mkdir backup
cd backup

Solution

1. Step 1: Create the folder first

   The command mkdir backup creates the folder named backup in the current directory.

2. Step 2: Change directory into the new folder

   After creating it, cd backup moves you inside that folder.

3. Step 3: Check other options

   cd backup mkdir backup tries to cd into backup before it exists, causing an error. mkdir cd backup misses the folder name in mkdir. cd backup cd backup tries to cd twice without creating the folder.

4. Final Answer:

   mkdir backup cd backup -> Option D

5. Quick Check:

   Create then cd = mkdir then cd [OK]

Hint: Always mkdir before cd into new folder [OK]

Common Mistakes:

• Trying cd before mkdir
• Omitting folder name in mkdir
• Repeating cd without folder