Modern-day Linux is super user-friendly, but to unlock its full potential, you need to familiarize yourself with some advanced concepts. Let’s look at seven key topics to elevate you from a casual Linux user to a power user.
1Shell, Bash, and Scripts
Ashellis defined as a command-line interpreter. It’s the program that takes the commands you type into a terminal/console, converts them into instructions the kernel can process, and then sends back the output to the terminal/console.
Most Linux systems useBash (Bourne Again SHell)as the default shell—because it’s versatile and sufficient for casual use. However, there are other shells available, likeZsh, Ksh, fish, and Tcsh. To check what shell you’re running, type “echo $SHELL” into the terminal.
Now,ashell scriptis a file containing a series of commands. These commands are executed in sequence when you run the script from the terminal. This can be a powerful automation tool on Linux, allowing you to bundle complex tasks into a single command.
2X11, Wayland, and XWayland
X11has been the default windowing system protocol forLinux and Unix-likeoperating systems since it was introduced in the mid ’80s. It uses a client-server model. The app windows you interact with are called “clients.” The “server,” aka the X server, processes input events from these clients, e.g., window movements, and then outputs how the client should respond. X11 is the windowing system protocol that carries the user input from the client to the X server and the output back to the clients.
Now,Waylandis a more modern (developed in 2008 by Red Hat) display server protocol.It simplifies the client-server architecture, enhancing security and performance. It allows the application window to directly communicate with the compositor (more about that in the next section), thereby reducing overhead and latency. The simplified architecture is also poised to improve security.
At the time of writing, most popular distros have migrated to Wayland. However, some applications optimized for X11 aren’tyetcompatible with Wayland. To solve this, we haveXWayland—a compatibility layer, enabling X11 applications to run in a Wayland environment.
To check if your system is using Wayland or X11, enter the following command into your terminal:
3Window Managers and Compositors
Have you ever moved an app window on Linux, only to find the borders of the window move while the inside remains empty and takes a few seconds to render? This happens when the window borders behave as expected, but the visuals inside the window take too long to render.
You see, the window borders and the visuals inside the window can be controlled by two separate systems, especially in X11 systems. To control the placement and appearance of windows on your screen, you havewindow managers. They allow you to move, resize, minimize, and maximize windows, as well as display window borders and title bars.
On the other hand, we havecompositors. They’re responsible for rendering the content inside each window. A compistor combines the final rendered image from the application with graphical effects like transparency, shadows, and animations to create a single image that is displayed inside the windows.
In traditional X11 environments, the window manager and compositor are usually separate components. This modular approach offers flexibility but can also lead to more complexity and potential system instability—like the example I shared earlier.
To fix this, Wayland combined the window manager and compositor into a single component—theWayland compositor. This simplifies the architecture, which can lead to better performance and security. A few examples of Wayland Compositors we see in regular distros running Wayland are:
4Custom Linux Kernels
We often refer to Linux as an operating system, but it’s actually thename of the kernelpowering the operating system. A kernel is basically the core of the operating system that bridges the hardware and the software. The official Linux kernel is maintained by Linux Torvalds and the Linux community. However, in true Linux spirit, people have modified the official kernel to include performance optimizations, improved hardware support, or additional features.
You can potentially replace the official Linux kernel on your system with one of these custom kernels to get better performance. Most distros require you to manually compile the custom kernel and install it on your distro. However, some advanced distros likeManjaroandGarudagive you aGUI app for replacing the default kernelwith a custom one.
Here are a few of the most popular custom Linux kernels:
It can be a trial-and-error process to determine which custom Linux kernel works best with your specific hardware setup. It’s useful to try out different options and see how your system performs, sticking with the one that yields the best results.
Custom kernels may not receive updates as frequently as the mainline kernel, which could impact security and compatibility over time.
5Systemd and SysV Init
When you boot up your Linux system, the very first process to start is the init system—which has the Process ID (PID) of #1. Most modern Linux distros primarily use one of two init systems: SystemD or SysV Init. you’re able to check which init system your distro is using by running this command in your terminal:
If the output shows “systemd”, you are using SystemD. Whereas, if it shows “init,” you are using SysV Init.
SystemDis the newer, more common init system used by all popular distros, including Ubuntu, Fedora, and Arch Linux. It’s designed to be faster and more efficient. My current system running Garuda Linux, also uses SystemD. However, it has some technical issues which make itdivisive in the Linux community.
As a result, afew Linux distros avoid SystemDand use an older init system—SysV Init. Other popular init systems include runit, OpenRC, and Upstart. Each has its own unique approach to managing services and system initialization.
Knowing which init system you are using is crucial if you want to start (or stop) a particular service during system boot-up. For example, I ran into an issue whereUFW (Uncomplicated Firewall)would automatically get deactivated after rebooting. To solve this, I needed to use the init system to auto-start UFW during system boot. Since I was using SystemD I used thesystemctlcommand. But if I was using SysV, I would’ve needed theservicecommand.
6Filesystem Types
As you become more familiar with Linux, you’ll find that itsupports a wide variety of filesystems, unlike Windows, which primarily uses NTFS for its main filesystem and FAT or exFAT for external storage. Most Linux systems use ext4 by default, but there are other popular options.
Linux also uses secondary filesystems for specific purposes, such as tmpfs for temporary files in memory and vfat for boot partitions or Windows compatibility.
To check the filesystems your Linux distro is using, typedf -Tinto a terminal and hit Enter.
If you want tochange filesystemson an existing Linux system, you’ll need to back up your data and then format the partition(s) to your desired filesystem type.
7SELinux and AppArmor
Linux is famous for its security, but itisn’t invulnerable. If you have important files and data on your Linux PC, you should take an active role in ensuring it’s configured to be as safe and secure as possible. To do this, you need to learn aboutSELinuxandAppArmor. Both of these are Linux Kernel security modules that add an extra layer of security by restricting what applications can do, reducing the risk of exploitation of security vulnerabilities.
You getSELinuxby default in Fedora and Red Hat Enterprise Linux (RHEL). However, you can alsoinstall and configureit to run on another distro. This kernel security model was developed by the NSA and offers fine-grained control over applications' access to resources using mandatory access controls (MAC). It’s complex but offers comprehensive security, making it suitable for high-security environments.
Next, we haveAppArmor. It offers a simpler, path-based approach to security, making it easier to configure while still providing effective protection. AppArmor is thedefault on Ubuntuand SUSE Linux Enterprise Server (SLES). That said, if you’re using a different distro, AppArmor is available in all the major Linux repositories, and you caneasily install iton any Linux distro you like.
To use these security modules effectively, you’ll need to set up security policies that define the allowed actions for applications. Thiscomparison of AppArmor and SELinuxshould help you decide which is right for your needs and requirements.
Understanding these advanced Linux concepts is crucial for anyone looking to upskill from a casual user to a power user. By exploring the intricacies of shells, window systems, custom kernels, system initialization, filesystems, and security modules, you’ll gain a deeper appreciation for the flexibility and power of Linux.
