Linux is a powerful and flexible operating system, widely used for servers, desktops, and development environments. Whether you're a beginner or an experienced user, mastering key Linux commands can significantly enhance your productivity. This tutorial will guide you through the top 50+ Linux commands you must know, explaining their usage and options.
1. ls - List Directory Contents
The ls command is used to list files and directories within the current directory.
ls
ls -l: Lists in long format showing permissions, ownership, and size.
ls -a: Lists all files, including hidden files (those starting with .).
2. free - Display Memory Usage
The free command shows memory usage.
free -h
3. pwd - Print Working Directory
The pwd command displays the current directory's full path.
pwd
4. mkdir - Make Directory
The mkdir command creates a new directory.
mkdir new_directory
mkdir -p /path/to/directory: Creates nested directories.
5. rmdir - Remove Directory
The rmdir command removes an empty directory.
rmdir directory_name
6. rm - Remove Files or Directories
The rm command deletes files and directories.
rm file_name
rm -r directory_name: Recursively deletes a directory and its contents.
rm -f file_name: Forces deletion without confirmation.
7. cp - Copy Files or Directories
The cp command copies files or directories.
cp source_file destination
cp -r source_directory destination: Recursively copies a directory.
8. mv - Move or Rename Files or Directories
The mv command moves or renames files or directories.
mv old_name new_name
mv file_name /path/to/destination: Moves a file to a different directory.
9. touch - Create an Empty File
The touch command creates an empty file or updates the timestamp of an existing file.
touch new_file
10. cat - Concatenate and Display Files
The cat command displays the content of a file.
cat file_name
cat file1 file2: Concatenates multiple files and displays the output.
11. echo - Print Text to the Terminal
The echo command displays text or outputs data to a file.
echo "Hello, World!"
echo "text" > file_name: Writes text to a file, overwriting its content.
12. head - View the First Lines of a File
The head command displays the first 10 lines of a file by default.
head file_name
head -n 20 file_name: Displays the first 20 lines.
13. tail - View the Last Lines of a File
The tail command displays the last 10 lines of a file by default.
tail file_name
tail -n 20 file_name: Displays the last 20 lines.
tail -f file_name: Continuously displays new lines as they are added.
14. grep - Search Text in Files
The grep command searches for patterns within files.
grep "pattern" file_name
grep -r "pattern" directory_name: Recursively searches within a directory.
15. find - Search for Files and Directories
The find command searches for files and directories based on various criteria.
find /path -name "file_name"
find /path -type d -name "dir_name": Searches for directories.
16. locate - Find Files by Name
The locate command quickly finds files by name.
locate file_name
locate -i file_name: Case-insensitive search.
17. chmod - Change File Permissions
The chmod command modifies the permissions of a file or directory.
chmod 755 file_name
chmod +x file_name: Makes a file executable.
18. chown - Change File Ownership
The chown command changes the ownership of a file or directory.
chown user:group file_name
chown -R user:group directory_name: Recursively changes ownership.
19. df - Display Disk Space Usage
The df command shows the disk space usage of file systems.
df -h
df -h /path: Shows usage for a specific path.
20. du - Estimate File Space Usage
The du command estimates file space usage.
du -h
du -sh directory_name: Shows total usage of a directory.
21. ps - Display Running Processes
The ps command displays currently running processes.
ps aux
ps -ef: Another common format to view processes.
22. top - Real-Time Process Monitoring
The top command shows real-time system processes.
top
Press q to quit.
23. kill - Terminate Processes
The kill command sends signals to terminate processes.
kill process_id
kill -9 process_id: Forcefully kills a process.
24. pkill - Terminate Processes by Name
The pkill command terminates processes based on name.
pkill process_name
pkill -9 process_name: Forcefully kills processes.
25. killall - Terminate All Instances of a Process
The killall command kills all instances of a process.
killall process_name
26. ssh - Secure Shell for Remote Login
The ssh command connects to remote servers securely.
ssh user@remote_host
ssh -p port_number user@remote_host: Connects on a different port.
27. scp - Secure Copy for File Transfer
The scp command securely copies files between hosts.
scp file_name user@remote_host:/path
scp -r directory_name user@remote_host:/path: Copies directories.
28. rsync - Remote Sync
The rsync command synchronizes files and directories between locations.
rsync -avz source destination
rsync -avz source user@remote_host:/path: Synchronizes with a remote host.
29. tar - Archive Files
The tar command creates and extracts archives.
tar -cvf archive_name.tar file_or_directory
tar -xvf archive_name.tar: Extracts an archive.
30. zip/unzip - Compress and Decompress Files
The zip command compresses files, and unzip decompresses them.
zip archive_name.zip file_or_directory
unzip archive_name.zip
31. wget - Download Files from the Internet
The wget command downloads files from the internet.
wget http://example.com/file
wget -c http://example.com/file: Resumes an incomplete download.
32. curl - Transfer Data from or to a Server
The curl command transfers data from or to a server.
curl http://example.com
curl -O http://example.com/file: Downloads a file.
33. hostname - Display or Set the System's Hostname
The hostname command shows or sets the system’s hostname.
hostname
hostnamectl set-hostname new_hostname: Sets a new hostname.
34. uname - Display System Information
The uname command shows system information.
uname -a
uname -r: Displays the kernel version.
35. whoami - Display Current User
The whoami command shows the current logged-in user.
whoami
36. sudo - Execute a Command as Superuser
The sudo command executes a command with superuser privileges.
sudo command
sudo -i: Opens a superuser shell.
37. apt-get - Package Management for Debian-based Distributions
The apt-get command installs, updates, and removes packages on Debian-based systems.
sudo apt-get update
sudo apt-get install package_name
sudo apt-get remove package_name: Removes a package.
38. yum - Package Management for RHEL-based Distributions
The yum command manages packages on RHEL-based systems.
sudo yum update
sudo yum install package_name
sudo yum remove package_name: Removes a package.
39. dnf - Updated Package Management for RHEL-based Distributions
The dnf command is a modern replacement for yum on RHEL-based systems.
sudo dnf update
sudo dnf install package_name
40. service - Control System Services
The service command starts, stops, and manages system services.
sudo service service_name start
sudo service service_name stop: Stops a service.
41. systemctl - Control the System and Service Manager
The systemctl command manages systemd services and configurations.
sudo systemctl start service_name
sudo systemctl enable service_name: Enables a service to start at boot.
42. passwd - Change User Password
The passwd command changes the password of a user.
passwd
sudo passwd user_name: Changes the password for another user.
43. useradd - Add a New User
The useradd command creates a new user.
sudo useradd new_user
sudo useradd -m new_user: Creates a new user with a home directory.
44. usermod - Modify a User Account
The usermod command modifies a user account.
sudo usermod -aG group_name user_name
sudo usermod -l new_name old_name: Changes a user's username.
45. userdel - Delete a User Account
The userdel command deletes a user account.
sudo userdel user_name
sudo userdel -r user_name: Deletes a user and their home directory.
46. groupadd - Add a New Group
The groupadd command creates a new group.
sudo groupadd new_group
47. groupdel - Delete a Group
The groupdel command deletes a group.
sudo groupdel group_name
48. crontab - Schedule Jobs
The crontab command schedules tasks to run at specific times.
crontab -e
crontab -l: Lists scheduled jobs.
49. alias - Create Shortcuts for Commands
The alias command creates shortcuts for commands.
alias ll='ls -l'
unalias ll: Removes an alias.
50. history - View Command History
The history command displays the list of previously executed commands.
history
!number: Re-executes a command from history by its number.
Conclusion
In this guide, we’ve covered some of the most essential Linux commands that every user should know. These commands are the building blocks for managing and interacting with your Linux system effectively. Whether you're a beginner or an experienced user, mastering these commands will greatly enhance your productivity and confidence when working in a Linux environment. Remember, the power of Linux lies in its versatility and control, and by familiarizing yourself with these tools, you’ll be well-equipped to harness the full potential of your system. Keep practicing, and don't hesitate to explore more advanced commands as you grow more comfortable with the basics. Happy Linuxing!
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