Master Linux administration, command-line tools, system configuration, and single-machine systems. Explore our full academy at: https://www.systutorials.com/linux-systems-admin-academy/
GCC allows you to embed assembly code directly in C/C++ programs through inline assembly (asm and __asm__). This is useful when you need fine-grained control over processor execution—forcing variables into specific registers, reading CPU state efficiently, or hand-optimizing critical sections verified by profiling. Basic Syntax GCC uses AT&T syntax by default on x86/x86-64. The simplest…
The GNU C Reference Manual is the authoritative resource for C as implemented by GCC. It’s a pure reference—not a tutorial—covering every linguistic construct, GCC-specific extensions, and implementation details you’ll encounter when compiling C code. What the Manual Covers The GNU C Reference Manual documents: All C language keywords and their behavior Operator precedence and…
cgdb is a curses-based frontend to gdb that keeps your source code visible while you debug. Unlike raw gdb, it splits the interface into two panes: source code on top, gdb command prompt below. If you’re already comfortable with Vim keybindings, cgdb feels natural—it uses the same navigation keys and modal editing paradigms you’re used…
Vim’s indentation system provides multiple approaches for formatting C/C++ code, from built-in operators to external formatters. The native tools work reliably for most tasks, while external formatters enforce stricter style rules when needed. The Indentation Operator and Text Objects The = operator re-indents text. It requires a motion or text object to specify what to…
The C language itself provides no built-in mechanisms for input/output, memory management, string manipulation, or process control. These essential capabilities come from the C standard library — a collection of functions, macros, and data types that you link with your programs at compile time. The GNU C Library (glibc) is the standard C library used…
When debugging and optimizing C/C++ programs, you need to see how the compiler translates your source code into assembly. A mixed source and assembly listing lets you trace exactly what machine instructions correspond to each line of your source. Using objdump (Recommended Modern Approach) The most straightforward method is to compile with debugging symbols and…
Self-hosting WordPress gives you control over your domain, design, content, and monetization—something you don’t get with WordPress.com or other hosted solutions. The reality: it’s feasible on a tight budget, but free hosting isn’t the answer. Why Self-Host? Hosted solutions lock you in. You can’t control your domain, customize templates deeply, manage backups reliably, or implement…
Insert the installation media and create a mount point: sudo mkdir -p /media/dvd sudo mount /dev/sr0 /media/dvd For a DVD image file instead of physical media: sudo mount -o loop /path/to/image.iso /media/dvd Verify the mount and check that packages exist: ls /media/dvd/Packages/ | head On systems with automatic mounting (systemd-based), the DVD may already be…
Running the same command across dozens of servers is a routine task in infrastructure work. Whether you’re checking disk usage, deploying updates, or gathering system metrics, doing this manually wastes time and introduces errors. The straightforward approach: iterate through a list of hosts and execute commands via SSH on each one. Basic Shell Loop Approach…
When managing multiple servers, you need reliable ways to verify which hosts are reachable. While orchestration tools like Kubernetes and Ansible handle monitoring at scale, a lightweight Bash script works well for quick spot checks, operational tasks, or smaller deployments. Basic ICMP Reachability Check The simplest approach uses ping to test ICMP reachability: ping -W…
Emacs provides a built-in tutorial. Access it with: C-h t For structured learning, the GNU Emacs Manual (built-in via C-h i) is the most authoritative resource. The Emacs Wiki also maintains community-driven guides and examples. Emacs configuration Store your configuration in ~/.emacs.d/init.el rather than the legacy ~/.emacs file. This keeps your Emacs directory cleaner and…
Qt and GTK applications often use different cursor themes, which creates visual inconsistency across your desktop. This mismatch is common in mixed-DE environments where Qt applications (like VLC, KeePass, or Telegram) inherit the wrong cursor style from system defaults. How Qt finds cursor themes Qt applications read cursor configuration from ~/.icons/default/index.theme. This file specifies which…
The diff utility generates unified diffs that show changes between file versions. Always use the -u flag to create unified diffs, which are the standard format for patches. For a single file: diff -u original.c new.c > fix.patch For an entire directory tree: diff -rupN original/ new/ > patchfile.patch The flags break down as: -r:…
The mupdf package is available in most major Linux distributions. On RHEL/CentOS/Fedora: sudo dnf install mupdf mupdf-tools On Debian/Ubuntu: sudo apt install mupdf On Arch: sudo pacman -S mupdf mupdf is a lightweight, fast PDF and XPS viewer written in C. It’s significantly faster than heavier alternatives like Evince or Okular, making it ideal for…
Xen remains in production use across cloud providers (AWS EC2, Citrix Hypervisor) and large infrastructure deployments, though KVM has become the default hypervisor for most Linux distributions. This guide covers installing a Fedora Domain-U on a Xen Dom0 using PXE boot, applicable to current Fedora releases. Prerequisites A working Xen Dom0 installation LVM backing store…
Modern Fedora (29+) uses firewalld by default instead of the legacy iptables service. If you’re working with an older system or one configured for iptables, the concepts here still apply, but you should first check what’s actually managing your firewall: systemctl status firewalld systemctl status iptables If firewalld is active, use firewall-cmd instead. For iptables-based…
Fedora switched to systemd for service management years ago, replacing the traditional /etc/inittab file with a target-based system. While systemctl set-default is the standard approach, understanding the manual method gives you insight into how systemd actually manages boot targets. Systemd Targets vs. Legacy Runlevels Systemd uses targets instead of runlevels. The two primary targets you’ll…
The startx command launches an X session without a display manager, reading configuration from $HOME/.xinitrc. By default, this file doesn’t exist—startx falls back to system defaults that typically only recognize GNOME or KDE. If you’ve installed MATE and want to use it with startx, you need to create a user-level configuration. Understanding startx Initialization When…
If your Linux machine is getting noticeably slower WiFi speeds than other devices on the same network, MTU (Maximum Transmission Unit) misconfiguration can be a culprit. While MTU tuning won’t be the answer in every case, it’s worth investigating if you’re seeing symptoms like high latency, dropped packets, or intermittent connection issues. Understanding MTU MTU…
Copying text to a file is a common operation on Linux, and there are several approaches depending on your workflow. Opening an editor like vim or nano works fine, but for quick pastes there are faster methods worth knowing. The Quick Clipboard Method If you have text copied to your clipboard, the fastest way to…