Quick Reference: Linux Cheat Sheet

Welcome back to our Linux journey! We covered the basic intro to understand LINUX.

In Part 1, we’ll dive a bit deeper. Whether you're curious about the Linux file system structure or command-line utilities that power day-to-day tasks, this guide will help solidify your foundation. If you’re a system administrator, DevOps engineer or just passionate about Linux, these commands will help you work smarter and with greater control over your environment.

Linux commands can be categorized into several types based on their functionality. Here are some of the main types:

• System Information Commands

• User Commands

• Process Management Commands

• Disk and Storage Commands

• Networking Commands

• File and Directory Commands

System Information Commands in Linux are commands that provide detailed information about the system's hardware, kernel, CPU, memory, disk usage, USB devices, and other core components.

Here are some commonly used Linux system information and management commands with their key functions:

uname : To know which type of OS you are using.
uname -a : To know full system info including kernel version and hostname.(“a” = all)
uname -r : It displays the kernel release version of your OS. (“r” = release)
uname -v : It also displays the version of the operating system's kernel build.
uname -n : It shows the network node hostname of your system.
uname -m : It displays machine hardware name(Architecture of system's CPU).

hostname : Displays the system's hostname and related network names.
hostname -i : To display the IP address(es) assigned to the host.
hostname I : To display the IP address(es) assigned to the host.
sudo hostname XYZ : Changes the runtime hostname of the system to XYZ.
hostnamectl set-hostname XY : Changes runtime hostname of the system to “XY“.

uptime : Shows how long the system has been running along with load averages.
uptime -p : Shows how long the system has been running (Only time will display).
uptime -s : Only date & time will display.
uptime -V : It display the version information of the uptime command itself.

User Commands:
w : Displays who is logged in and what they are doing.
who : Used to show who is currently logged into the system.
whoami : Shows the current logged-in username.
id : Shows user ID (UID), group ID (GID), etc.

Process Management Commands: Monitor and control running processes.
top : Real-time system process viewer.
q : quit.
ps : Shows a snapshot of current running processes.
ps aux : List all running processes.
last reboot : Shows the history of system reboots on your Linux machine.
kill -9 PID : Used to forcefully terminate a process by its PID.

Disk and Storage Commands:
df :(disk free): Used to report disk space usage of file systems.
df -h : Display disk space usage in a human-readable format.
du : Displays disk usage (space used by files and directories).
du -h : Displays disk usage of files and directories in a human-readable format.
du -sh : Display the total size of a directory or file in a human-readable format.
du -ah : Displays disk usage of all files and directories, in human-readable format.
lscpu : Displays detailed information about the CPU architecture of your system.
cat /proc/cpuinfo : Display detailed information about the CPU(s) on your system.
lsblk : Lists information about block devices (like hard drives, SSDs, USB drives).
lsblk -a : Lists all devices (including empty ones).
free : Displays system memory usage, including RAM and swap.
cat /proc/cpuinfo : Displays system memory usage, including RAM and swap.
free -m : Displays system memory usage in megabytes (MB).
free -g : Displays system memory usage in gigabytes (GB).

Networking Commands:
ip addr : Used to display all IP addresses and network interfaces on a Linux system.
ip config : Used to display or configure network interfaces on Unix/Linux systems.
ip route : Shows how network traffic is directed.

Time and Date management commands:
timedatectl : Displays current system time, local time, UTC time.
timedatectl set-timezone “Asia/Kolkata” : Is used to change the system's time zone.

DATE Commands:
date : To get today’s date.
date +“%d" : Displays the current day of the month in two-digit format.
date +”%y” : Displays the current year in two-digit format.
date +”%m” : Displays the current month as a two-digit number.
date +”%b” : Displays the abbreviated month name.
date +"%p" : Displays the current AM or PM indicator for the 12-hour clock.
date +”%A” : Display the full name of the current day of the week.
date +“%B” : Displays the full name of the current month.
date +”%D” : Displays the current date in MM/DD/YY format.
date +”%F” : Displays the full date in ISO format.
date +“%H” : Displays the current hour in 24-hour format.
date +”%T” : Displays the current time in 24-hour format (HH:MM:SS).
date +"%I" : Displays the current hour in 12-hour format.
date +”%M” : Displays the current minute.
date +”%S” : Displays the current seconds.

Basic Commands :
sudo -i : To login as root user (Super User Do - sudo)
clear : It clears the terminal screen (shortcut → Contrl+L).
exit : Close the current shell or terminal session.

CONCLUSION
Linux isn’t just an operating system—it’s a mindset. Each command you learn is a small victory, building your confidence and deepening your understanding of how machines respond to human logic. These tools may seem simple, but they open doors to automation, problem-solving, and creativity.

Whether you're a curious explorer or an aspiring system pro, your journey with Linux is uniquely yours. Embrace the command line not just as a tool, but as a space where learning, growth, and empowerment come together.

Every line you enter is a chance to discover, create, and grow. Keep experimenting. Share what you learn. Stay tuned for future posts where we’ll explore more Linux commands in next part. Thanks for reading.

💡 Happy typing—and may your terminal always respond with exactly what you need.