Bash provides comparison operators for conditionals through the test command (aliased as [), the [[ ]] compound command, and the (( )) arithmetic command. Each has specific use cases and behavior differences worth understanding. String Comparisons String comparisons work with test/[ and [[ ]]: Operator Meaning -n STRING String length is nonzero (true if not…
IEEE requires a specific format for web citations, and BibTeX handles this cleanly with the @online entry type. Here’s how to get it right. IEEE Web Citation Format IEEE specifies this pattern for online sources: [#] Initial(s). Surname, “Title [Online]. Available: URL. Accessed: Month Day, Year.” A complete example looks like: [1] J. Jones, “Networks…
When debugging a program or understanding what it actually touches on your filesystem, you need to see which files it opens. Two tools do this well: strace traces system calls in real time, while lsof inspects a running process without the overhead. Using strace to capture file operations The simplest approach is to run strace…
SSH is fast enough for most tasks, but when you’re transferring large files, running multiple commands, or managing hundreds of servers, every millisecond counts. Here’s how to squeeze real performance gains from SSH and SCP on Linux. Choose the Right Cipher Cipher selection has the biggest impact on throughput. Modern CPUs have AES-NI hardware acceleration,…
When you need to reach a server through one or more intermediate hosts, you can establish a direct connection without manually chaining SSH sessions. This is essential for accessing internal servers that aren’t directly reachable from your workstation. The scenario laptop —-> proxy —-> server You want to connect to server.example.com through proxy.example.com as if…
The Windows (Super) key can be remapped to function as an additional Ctrl key, useful if you work across multiple systems or prefer the extra modifier. The approach varies significantly by display server and desktop environment. GNOME (Wayland and X11) GNOME 3.38 and later have built-in remapping through Settings: Open Settings → Keyboard → Special…
Remapping modifier keys on Linux makes sense if you’re an Emacs power user, prefer ergonomic hand positioning, or simply don’t use the Win key. The standard approach moves frequently-used modifiers closer to your thumbs by trading the underutilized Super/Win key for additional Ctrl or Alt access. A typical remapped layout looks like: |Ctrl|Alt|Ctrl| Space Bar…
Remapping space to Ctrl while preserving space on tap is useful for modal editors and power users. The challenge: distinguish between a held key (Ctrl) and a quick tap (space). Kernel-level remapping can’t do this, so you need userspace solutions. Quick Comparison of Methods Tool Best For Pros Cons keyd Simplicity, both X11 and Wayland…
Emacs makes heavy use of Ctrl, and many users find it ergonomically difficult to hit Ctrl repeatedly, especially on modern keyboards where Ctrl is placed far from home row. Swapping Alt and Ctrl can make Emacs navigation more comfortable. This guide covers modern approaches for different desktop environments and input systems. Emacs-Only Configuration (Simplest) If…
Memory leak detection is critical for C program reliability. Several tools work at different stages of development—compile time, runtime, and production scenarios. Your choice depends on performance tolerance, integration needs, and how much detail you require. AddressSanitizer (ASan) AddressSanitizer is the first tool to reach for in 2026. It’s compiler-integrated, fast, and catches a broader…
If you’re running a dual-boot system with Windows, you’ll need to configure which operating system loads by default. The method depends on your Windows version and whether you’re using legacy BIOS or UEFI firmware. Windows 7 and Vista: System Properties Method For Windows 7 systems using the traditional boot manager: Open Control Panel and navigate…
Remapping Caps Lock to Control is a worthwhile investment if you spend significant time in Emacs or vim. Your pinky will benefit from years of reduced strain. Desktop Environment Settings (Easiest) Most modern desktop environments include a built-in option for this remapping. GNOME (40+): Open Settings → Keyboard → Special Character Options Toggle “Make Caps…
dd is a powerful utility for reading and writing raw data to block devices. While it’s a Linux standard, you have several options for using it on Windows systems. WSL2: The Modern Approach For Windows 10 (21H2+) and Windows 11, Windows Subsystem for Linux 2 (WSL2) is the best choice. It provides a full Linux…
When network interfaces fail or behave unexpectedly, you need to inspect driver details, hardware state, and kernel messages. Here’s the practical toolkit for diagnosing network hardware and driver issues. Kernel Messages and Logs Start by checking kernel logs where driver initialization and errors are recorded: dmesg | grep -i network dmesg | grep -i driver…
The @ symbol in Makefiles suppresses the echo of the command itself before execution. When you run a target, make normally prints each command to stdout before running it. Adding @ before a command hides that echo, showing only the command’s output. Basic example Without @: all: echo “For correctness test of basic get and…
The most reliable one-liner to count files in the current directory is: find . -maxdepth 1 -type f | wc -l This counts only regular files (not directories or symlinks) and handles edge cases that trip up simpler approaches. Why Not Use ls | wc -l? The common ls | wc -l command has several…
Parsing directory and filename components from an absolute path is a common task in systems programming. Linux provides dirname() and basename() functions for this purpose, but they have implementation-specific behaviors that can cause bugs if you’re not careful. Using dirname() and basename() The POSIX standard defines both functions, though the implementations vary. Here’s the safest…
Exit codes are how programs communicate success or failure to the shell and parent processes. Understanding them is essential for writing reliable scripts and debugging applications. Linux and Windows handle these differently, so knowing both conventions matters if you work across platforms. Linux Exit Codes On Linux, the convention is simple: 0 means success, 1–255…
The lp command is the standard tool for printing from the Linux command line. It interfaces with CUPS (Common Unix Printing System), the printing backbone on virtually all modern Linux distributions. Basic Printing Send a file to your default printer: lp text-file.txt Specify a particular printer: lp -d printer-name text-file.txt List available printers and identify…
Bash doesn’t have a goto statement, and that’s intentional. The language is designed to encourage cleaner control flow patterns that are easier to debug and maintain. When you feel the urge to jump around in your script, there’s almost always a better approach. Functions and Early Return The cleanest pattern is extracting logic into functions…