On most distributions: # Debian/Ubuntu sudo apt install xvkbd # Fedora/RHEL sudo dnf install xvkbd # Arch sudo pacman -S xvkbd xvkbd is an X11 tool for sending keyboard and mouse input to the focused window. It’s lightweight and useful for straightforward automation tasks, but has significant limitations that make it unsuitable for critical workflows….
The No-IP client automatically synchronizes your domain with your current public IP address. This is essential when hosting services on machines with DHCP-assigned IPs or when you need reliable DNS without paying for static IP assignments. Installation From Package Repositories Most distributions package noip2 in their standard repos: Debian/Ubuntu: sudo apt install noip2 Fedora/RHEL/CentOS: sudo…
ASCII stands for American Standard Code for Information Interchange. It’s a 7-bit character encoding standard mapping numeric values (0-127) to printable characters and control codes. Since computers work with numbers at the lowest level, ASCII provides a universal way to represent text—each character has a unique numeric value. Standardized in 1963, ASCII remains foundational to…
GNOME Classic is a session mode that provides a traditional desktop experience with an application menu, places menu, and window switcher. It’s useful if you prefer a layout closer to GNOME 2 or want a traditional taskbar-based interface instead of GNOME Shell’s Activities overview. Installation The gnome-classic-session package isn’t installed by default. Install it with…
Symbolic links (symlinks) are aliases that point to other files or directories. Most operations treat them transparently—programs reading or writing through a symlink behave as if working with the target directly. Understanding how to create, test, and manage them correctly is essential for system administration. Creating Symbolic Links Create a basic symlink: ln -s ../target…
Thunderbird’s default reply headers are minimal—just a simple line showing who sent what and when. If you need detailed formatted headers showing From, To, Cc, Subject, and Date for compliance, audits, or professional correspondence, you’ll need to add an extension or configure a template. ReplyWithHeader Extension ReplyWithHeader is the quickest solution. It replaces Thunderbird’s default…
iPhone’s automatic screen rotation is useful most of the time, but it gets annoying when you’re reading in bed, watching video in a fixed orientation, or using apps that work better in portrait mode. iOS gives you straightforward ways to lock rotation when you need it. Quick Lock Through Control Center The fastest way to…
Printing PDF annotations with fidelity across different readers requires understanding each tool’s specific workflow. The fundamentals haven’t changed much, but modern versions offer more reliable options than they did years ago. Adobe Acrobat (Full Version) Acrobat provides the most control over annotation printing, but requires explicit configuration before print. Enable annotation printing in preferences: Open…
The Nokia E71 includes native POP3 and IMAP support without requiring additional messaging apps. This guide covers manual configuration of both protocols with modern best practices. Initial Setup Navigate to Menu → Communic. → Messaging → Options → Settings → E-mail → Options → New mailbox → Start. When prompted “Allow connection?”, select NO. This…
Thunderbird’s most powerful settings live outside the UI—buried in the config editor or preferences file. This guide covers setting emails to sort newest-first by default and enabling inline quoting for replies, two changes that significantly improve daily usability. Accessing the Config Editor Open the config editor at Edit → Preferences → Advanced → Config Editor,…
By default, closing the last tab in Firefox also closes the entire browser window. You can change this behavior through Firefox’s preferences so the browser stays open with an empty window. Access about:config Open Firefox and type about:config in the address bar. Firefox displays a warning about modifying preferences—this is expected and safe. Click “Accept…
Firefox’s extension ecosystem is mature enough that you should install conservatively. Each extension consumes memory, introduces potential compatibility issues, and creates another surface for security problems. The extensions listed here solve genuine problems; install only what you use. Ad Blocking uBlock Origin remains the standard. It uses significantly less memory than alternatives and supports complex…
Running an SSH server on Windows enables remote administration, port forwarding, and integration with Unix-like workflows. Modern Windows provides native OpenSSH support that’s far superior to legacy third-party solutions. Installation Windows 10 (build 1809+), Windows 11, and Windows Server 2019+ include OpenSSH as an optional feature. Via Settings: Open Settings → System → Optional features…
Bash has no native floating point support. The (( )) and $(( )) arithmetic expansions only handle integers. For decimals, you need external tools — primarily bc, awk, or dc. bc: Arbitrary Precision Calculator bc is the standard choice for floating point math in shell scripts. It’s POSIX-compliant, available on every Unix-like system, and handles…
Make is a build automation tool that reads configuration files (makefiles) to compile programs and manage project workflows. It’s been a standard in Unix/Linux development for decades and remains essential for managing builds where dependencies matter. Make works by defining targets and their dependencies, then specifying commands to build each target. When you run make,…
When building applications requiring fast key-value lookups, hash tables are fundamental. C offers several options—from POSIX standard library functions to specialized third-party libraries. The right choice depends on your dataset characteristics, memory constraints, and whether you need dynamic resizing. Standard Library: hsearch() The simplest option is hsearch() from <search.h> in POSIX-compliant systems. It provides basic…
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…
fclose() closes a file stream and disassociates it from its underlying file descriptor. It’s part of the C standard library, defined in <stdio.h>. #include <stdio.h> int fclose(FILE *stream); When called, fclose() flushes buffered output, closes the file descriptor, and deallocates the FILE structure. The function works with both input and output streams. After fclose() returns,…