50 Essential Linux Commands for Beginners and SysAdmins

For someone new to Linux, using it can still feel challenging, even with user-friendly distributions like Ubuntu and Mint.

While these distributions simplify many tasks, some manual configuration is often required, but fully harnessing the power of Linux, understanding basic commands is essential.

In Linux, commands are the primary way to interact with the system and allow users to perform tasks, configure settings, and manage the system efficiently.

This guide introduces 60 essential Linux commands, providing a foundation for beginners and a pathway to becoming a skilled system administrator. These commands cover a wide range of functions, from navigating directories and managing files to performing advanced system operations.

Whether you’re just starting out or aiming to deepen your expertise, these commands will help you unlock the full potential of Linux.

Basic Linux Commands and Examples for Newbies

Whether you’re a beginner or an advanced user, mastering basic Linux commands is essential for navigating and controlling the operating system.

Below are some commonly used Linux commands along with their descriptions and examples:

1. View the Contents of a Directory

The ls command is used to view the files and directories within a specified directory, it can display both visible and hidden files (files starting with . are hidden by default).

Additional options can provide detailed information like file permissions, ownership, size, and modification dates.

ls -la

2. Viewing Blocks, HDD Partition, External HDD

The lsblk command displays information about block devices such as hard drives, partitions, and external drives in a tree-like format.

lsblk

3. Checking the Integrity of Downloaded/Transferred Packages

The sha256sum or md5sum commands generate and verify cryptographic hash values for files, which ensures the file’s integrity after downloading or transferring.

sha256sum file.tar.gz

4. Converting and Copying a File

The dd command is used for low-level file copying and conversion, which is often employed to create bootable USB drives or clone disk images.

dd if=input.img of=output.img bs=4M status=progress

5. Know Your Machine Name, OS, and Kernel

The uname command provides system information, including the kernel version, system architecture, and hostname.

uname -a

6. Viewing History of Commands

The history command lists previously executed commands, allowing you to recall or reuse them.

history

7. Run Commands as Root User

The sudo command allows users to execute commands with administrative privileges. Use sudo -i to switch to a root shell.

sudo -i

8. Make a New Directory

The mkdir command creates a new directory with the specified name in the current location.

mkdir my_folder

9. Create or Update File Timestamps

The touch command creates empty files or updates the timestamp of existing ones.

touch my_file.txt

10. Changing the File Permission

The chmod command changes file permissions, controlling who can read, write, or execute a file.

chmod 644 my_file.txt

11. Change File Ownership

The chown command changes file ownership and group ownership.

sudo chown user:group my_file.txt

12. Install, Update, and Maintain Packages

The apt command manages software packages on Debian-based systems.

sudo apt update && sudo apt install package_name

13. Uncompressing a Tar File

The tar command extracts compressed files.

tar -xvzf file.tar.gz

14. See Current Date, Time, and Calendar

The date and cal commands display the current date, time, and calendar.

date
cal

15. Print Contents of a File

The cat command prints the contents of a file to the terminal.

cat my_file.txt

16. Copy and Move Files

The cp and mv commands copy and move files, respectively.

cp source.txt destination.txt
mv old_name.txt new_name.txt

17. See the Working Directory for Easy Navigation

The pwd command prints the current directory path.

pwd

18. Change the Working Directory

The cd command navigates between directories.

cd /path/to/directory

Advanced Linux Commands for Intermediate Users

Once you’ve mastered the basic Linux commands, it’s time to dive deeper into more advanced commands that will help you manage and optimize your system more efficiently.

19. Finding a File in a Given Directory

The find command is used to search for files and directories within a specified directory or across the entire file system.

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

20. Searching a File with the Given Keywords

The grep command is used to search for specific patterns (keywords) within files, which is highly useful when you want to find specific information inside a file or a set of files.

grep "keyword" filename

21. Finding Online Documentation

The man command displays the manual or help documentation for a specific command, which provides detailed information about how to use a command, its options, and its syntax.

man ls

22. List Current Running Processes

The ps command shows a snapshot of the current processes running on your system with details like process IDs (PIDs), memory usage, and CPU usage.

ps aux

To list all processes related to Firefox, using grep to filter the output.

ps aux | grep firefox

23. Kill a Running Process

The kill command is used to terminate a running process by specifying the process ID (PID) of the process you want to terminate.

kill 1234

24. See the Location of Installed Binaries

The which command helps locate the path of executables in your system’s PATH by searching through the directories listed in the PATH environment variable and returns the location of the executable.

which python3

25. Starting, Ending, Restarting a Service

The systemctl command is used to manage system services (also known as daemons) on systems using systemd.

systemctl start service_name
systemctl stop service_name
systemctl restart service_name

26. Creating and Removing Command Aliases

Aliases are shortcuts for commands, which can save time by reducing the amount of typing and the alias command creates a shortcut, while unalias remove it.

alias shortcut_name='command'
unalias shortcut_name

You can create an alias for a command with a custom name.

alias ll='ls -l'
unalias ll

This creates an alias ll for the ls -l command, which lists directory contents in a long format.

27. View Disk and Space Usage

The df command shows disk space usage for all mounted file systems by providing information about the total space, used space, and available space.

df -h

28. Removing a File and/or Directory

The rm command is used to remove files and directories. You can use the -r option to remove directories and their contents recursively.

rm filename
rm -r directory_name

29. Print/Echo a Custom Output on Standard Output

The echo command is used to print text or the value of a variable to the terminal.

echo "Custom Message"

30. Changing Password in Linux

The passwd command is used to change passwords for the current user or other users (if you are the root user).

passwd username

31. View Printing Queue

The lpq command shows the status of the printing queue, including any pending or completed print jobs.

lpq

32. Compare Two Files

The diff command compares two files line by line and displays the differences between them.

diff file1 file2

33. Download a File, the Linux Way (wget)

The wget command is used to download files from the internet, it supports HTTP, HTTPS, and FTP protocols.

wget https://example.com/file.zip

34. Mount a Block/Partition/External HDD

The mount command is used to attach a block device (e.g., a hard drive or USB drive) to a directory in the filesystem.

mount /dev/sdX /mnt

35. Compile and Run C, C , and Java Code

To compile and run code in C, C , and Java, you use the respective compilers and runtimes.

• C: gcc is used to compile C programs.c.
• C : g is used to compile C programs.
• Java: javac is used to compile Java programs, and java is used to run them.

To compile and run C code:

gcc -o outputfile sourcefile.c
./outputfile

To compile and run C code:

g   -o outputfile sourcefile.cpp
./outputfile

To compile and run Java code:

javac filename.java
java filename

Advance Linux Commands for Linux Sysadmins

In the last section of this series, we tried to cover the commands that needed to administer a Linux server.

36. Configuring Network Interface

The ifconfig command is used to allow you to set up, manage, and display network interface parameters, which is typically used to assign IP addresses, configure network interfaces, and troubleshoot network issues.

sudo ifconfig eth0 192.168.1.100 netmask 255.255.255.0 up

This command assigns the IP address 192.168.1.100 to the eth0 interface and brings it up.

37. Viewing Custom Network-Related Information

The netstat command provides detailed information about network connections, routing tables, interface statistics, and more.

netstat -tuln

38. Fetching Data with curl

The curl command is used to transfer data from or to a server. It supports various protocols, including HTTP, FTP, and more. You can use it to fetch data from a web server or test server responses.

curl -I https://www.example.com

39. Checking DNS Information

The dig command is a DNS lookup utility that provides detailed information about DNS records, which is commonly used for troubleshooting DNS issues.

dig example.com

40. Knowing Your System Uptime

The uptime command shows how long the system has been running, the number of users logged in, and the system load averages for the past 1, 5, and 15 minutes.

uptime

41. Broadcast Messages to Logged-in Users

The wall command is used to send messages to all users currently logged into the system.

echo "System Maintenance in 10 minutes" | wall

42. Send Text Messages Directly to a User

The write command allows you to send a message to another logged-in user.

write username

43. Piping Commands Together

You can combine multiple commands using pipes (|) to pass the output of one command to another.

ps aux | grep firefox

44. Seeing the Processes of a CPU

The top command displays a dynamic, real-time view of system processes, including CPU and memory usage.

top

45. Creating a Newly Formatted ext4 Partition

The mkfs.ext4 command is used to create an ext4 file system on a partition.

sudo mkfs.ext4 /dev/sdb1

46. Editing Files with vi, emacs, and nano

In Linux, there are several text editors available for editing files directly from the command line. Among the most popular are vi, emacs, and nano.

To edit files with vi:

vi filename.txt

To edit files with emacs:

emacs myfile.txt

To edit files with nano:

nano myfile.txt

47. Copying a Large File/Folder with Progress Bar

The rsync command is used to copy files and directories. With the --progress option, it shows a progress bar.

rsync -avh --progress source_directory/ destination_directory/

48. Check Available Memory

The free command shows the amount of free and used memory in the system.

free -h

49. Backing Up a MySQL Database

The mysqldump command is used to create backups of MySQL databases.

mysqldump -u root -p database_name > backup.sql

50. Generate a Random Password

The openssl command can generate a random password.

openssl rand -base64 12

51. Merge Two Text Files

The cat command can be used to concatenate two text files into one.

cat file1.txt file2.txt > mergedfile.txt

52. List of All the Opened Files

The lsof command lists all open files and the processes that opened them.

lsof

These commands are fundamental tools for system administrators and users to interact with Linux systems efficiently.

The above is the detailed content of 50 Essential Linux Commands for Beginners and SysAdmins. For more information, please follow other related articles on the PHP Chinese website!