📚 Mastering Linux Commands: Basics to Advanced

Welcome to my adventure of helping people out there not familiar with these terms. Today we will dive into the world of Linux! Whether you're a beginner or looking to advance your skills, this guide is your go to cheat sheet for Linux commands, from basic to advanced. Let's dive in! 🚀

🟢 Basic Commands

1. cd - Change Directory

The cd command is used to change the current working directory.

Syntax:

cd [directory_name]

Examples:

cd /home/tanmaya   # Change to the /home/tanmaya directory
cd ..              # Move up one directory level
cd ~               # Change to the home directory

2. ls - List Directory Contents

The ls command lists the files and directories in the current directory.

Syntax:

ls [options/flags] [directory]

Examples:

ls              # List files in the current directory
ls -l           # List in long format
ls -a           # List all files, including hidden files

3. pwd - Print Working Directory

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

Syntax:

pwd

Example:

pwd             # Shows the current directory path

4. who - Show Who is Logged On

The who command shows who is currently logged into the system.

Syntax:

who

Example:

who             # Lists all logged-in users

5. whoami - Display Current User

The whoami command shows the username of the current user.

Syntax:

whoami

Example:

whoami          #Displays the current user's name. Eg: tanmaya, if done on my system.

6. touch - Create an Empty File

The touch command creates an empty file or updates the timestamp of an existing file.

Syntax:

touch [filename]

Example:

touch file.txt  # Creates an empty file named file.txt

7. mkdir - Make Directory

The mkdir command creates a new directory.

Syntax:

mkdir [directory]

Example:

mkdir test_tanmaya  #Creates a directory named "test_tanmaya"

8. cp - Copy Files

The cp command copies files or directories.

Syntax:

cp [source] [destination]

Examples:

cp file1.txt file2.txt  # Copy file1.txt to file2.txt
cp -r dir1 dir2         # Copy directory dir1 to dir2

9. mv - Move/Rename Files

The mv command moves or renames files or directories.

Syntax:

mv [source] [destination]

Examples:

mv file1.txt file2.txt  # Rename file1.txt to file2.txt
mv file.txt /home/user/ # Move file.txt to /home/user/

10. rm - Remove Files

The rm command deletes files or directories.

Syntax:

rm [options] [file]

Examples:

rm file.txt         # Delete file.txt
rm -r dir           # Delete directory dir and its contents

11. cat - Concatenate and Display Files

The cat command displays the contents of a file.

Syntax:

cat [file]

Example:

cat file.txt        # Display the contents of file.txt

12. echo - Display a Line of Text

The echo command displays a line of text or a variable value.

Syntax:

echo [text]

Example:

echo "Hello, World!"  # Prints "Hello, World!"

🟡 Intermediate Commands

13. nano - Text Editor

The nano command opens the Nano text editor, a simple and user-friendly editor.

Syntax:

nano [file]

Example:

nano file.txt      # Opens file.txt in Nano

14. vi - Text Editor

The vi command opens the Vi text editor, a more powerful but complex editor.

Syntax:

vi [file]

Example:

vi file.txt        # Opens file.txt in Vi

15. chmod - Change File Permissions

The chmod command changes the file permissions.

Syntax:

chmod [permissions] [file]

Example:

chmod 755 file.sh  # Sets read, write, execute for owner, and read, execute for group and others

16. chown - Change File Owner and Group

The chown command changes the owner and group of a file.

Syntax:

chown [owner]:[group] [file]

Example:

chown tanmaya:student file.txt  # Changes the owner to tannmaya and the group to student.

17. ps - Process Status

The ps command displays information about running processes.

Syntax:

ps [options]

Example:

ps aux           # Shows detailed information about all running processes

18. top - Display Task Manager

The top command shows real-time system information, including CPU and memory usage.

Syntax:

top

Example:

top              # Opens the real-time system monitor

19. kill - Terminate Processes

The kill command sends a signal to a process to terminate it.

Syntax:

kill [signal] [PID]

Example:

kill 1234        # Terminates the process with PID 1234

20. nice - Set Process Priority

The nice command starts a process with a specified priority.

Syntax:

nice -n [priority] [command]

Example:

nice -n 10 ./script.sh  # Runs script.sh with a priority of 10

21. vmstat - Report Virtual Memory Statistics

The vmstat command reports information about processes, memory, paging, block IO, traps, and CPU activity.

Syntax:

vmstat [options]

Example:

vmstat            # Shows a summary of virtual memory statistics

🔵 Advanced Commands

22. awk

awk is a powerful programming language for pattern scanning and processing. It is used to manipulate data and generate reports.

Syntax:

awk 'pattern {action}' filename

Example: Print the second column of a file:

awk '{print $2}' file.txt

Example: Filter lines containing "Info" and print the first and third columns:

awk '/Info/ {print $1, $3}' file.txt

23. sed

sed (stream line editor) is used for parsing and transforming text.

Syntax:

sed 's/pattern/replacement/' filename

Example: Replace "Linux" with "Unix" in a file:

sed 's/Linux/Unix/g' file.txt

Example: Delete lines containing "Linux":

sed '/Linux/d' file.txt

24. grep

grep searches for patterns within files and outputs the matching lines.

Syntax:

grep 'pattern' filename

Example: Find lines containing "error":

grep 'error' logfile.txt

Search recursively in all files within a directory:

grep -r 'error' /path/to/directory/

25. find

find searches for files and directories in a directory hierarchy.

Syntax:

find /path/to/search -name "filename"

Example: Find all .txt files in the current directory:

find . -name "*.txt"

Example: Find files larger than 10MB:

find /path/to/search -size +10M

26. scp

scp (secure copy) is used to copy files between hosts on a network.

Syntax:

scp source_file username@destination_host:/path/to/destination/

Example: Copy a file to a remote server:

scp file.txt user@remote:/path/to/destination/

Example: Copy a file from a remote server:

scp user@remote:/path/to/source/file.txt /local/path/

27. rsync

rsync is used for fast, incremental file transfer. Transfers only new changes done to the file.

Syntax:

rsync options source destination

Example: Synchronize a directory to a remote server:

rsync -avz /local/dir/ user@remote:/path/to/destination/

Example: Synchronize a remote directory to the local machine:

rsync -avz user@remote:/path/to/source/ /local/dir/

---

Learning these Linux commands will make you more efficient and capable as a DevOps engineer.

I hope I was able to deliver these commands in an easy way making you understand. Happy to connect for any queries!!