SysTutorials Posts

Design Patterns & Architecture

Understanding Hadoop Configuration Files: Locations and Defaults
ByEric Ma Mar 24, 2018Apr 13, 2026

Hadoop uses three primary configuration files to define YARN, HDFS, and MapReduce behavior: HDFS: hdfs-site.xml YARN: yarn-site.xml MapReduce: mapred-site.xml These files live in $HADOOP_HOME/etc/hadoop/ and override the built-in defaults when present. Finding Official Default Values Apache publishes default configuration documentation for each release. For current versions: Hadoop 3.4.x (Latest) HDFS defaults: https://hadoop.apache.org/docs/r3.4.0/hadoop-project-dist/hadoop-hdfs/hdfs-default.xml YARN defaults: https://hadoop.apache.org/docs/r3.4.0/hadoop-yarn/hadoop-yarn-common/yarn-default.xml…

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Web Development

Converting LaTeX Documents with Figures to HTML
ByEric Ma Mar 24, 2018Apr 12, 2026

Converting LaTeX to HTML while preserving figures is essential when publishing technical documentation online. The right tool depends on your document complexity and output requirements. tex4ht (htlatex) tex4ht is the most reliable option for LaTeX documents with figures, math, and complex formatting. It’s part of the TeX Live distribution and available on all major platforms….

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Linux & Systems Administration

Remapping Modifier Keys on Linux
ByEric Ma Mar 24, 2018Apr 12, 2026

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…

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System Administration & Cloud

Custom Headers and Footers in Apache Directory Listings
ByEric Ma Mar 24, 2018Apr 12, 2026

Custom headers and footers in Apache directory listings let you add branding, instructions, or navigation without modifying the core file listing. This is useful for public file archives, download directories, or any indexed directory you want to customize. Basic Setup with .htaccess Add these directives to .htaccess in the directory where you want custom listings:…

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Linux & Systems Administration

Remapping Windows Key to Ctrl on Linux
ByEric Ma Mar 24, 2018Apr 12, 2026

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…

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Linux & Systems Administration

Splitting Text Files by Lines on Linux: A split Command Guide
ByEric Ma Mar 24, 2018Apr 12, 2026

The split command is the standard tool for breaking large text files into smaller chunks on Linux. Here’s the basic syntax: split -l 1024 content.txt splitted-content.txt- This creates output files named splitted-content.txt-aa, splitted-content.txt-ab, and so on, with each containing 1024 lines. Understanding output naming By default, split appends two-character suffixes starting with aa. The naming…

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Design Patterns & Architecture

Configuring Hadoop Classpath for MapReduce Compilation
ByEric Ma Mar 24, 2018Apr 13, 2026

When compiling MapReduce jobs against a Hadoop installation, you need to include the correct classpath to resolve Hadoop dependencies. The yarn classpath command handles this automatically. Getting the classpath Run this command to output the full classpath: yarn classpath If yarn isn’t in your $PATH, use the full path: $HADOOP_HOME/bin/yarn classpath Replace $HADOOP_HOME with your…

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Linux & Systems Administration

Resetting Your Linux Keyboard Layout with xmodmap and setxkbmap
ByEric Ma Mar 24, 2018Apr 12, 2026

When you’ve modified your keyboard layout or key bindings using xmodmap and need to revert to the default, setxkbmap is your primary tool. However, the approach depends on whether you’re running X11 or Wayland, and what aspects of the configuration you want to reset. Check Your Session Type Before attempting any resets, verify whether you’re…

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Linux & Systems Administration

Memory Leak Detection Tools for C on Linux
ByEric Ma Mar 24, 2018Apr 12, 2026

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…

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Linux & Systems Administration

Remapping Alt and Ctrl Keys in Linux for Emacs
ByEric Ma Mar 24, 2018Apr 12, 2026

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…

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Linux & Systems Administration

Remap Space Bar to Ctrl with Tap-for-Space on Linux
ByEric Ma Mar 24, 2018Apr 12, 2026

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…

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Linux System Configuration

Changing the Default OS in a Windows Dual Boot Setup
ByEric Ma Mar 24, 2018Apr 12, 2026

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…

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Linux & Systems Administration

Remapping Caps Lock to Control on Linux: X11 and Wayland
ByEric Ma Mar 24, 2018Apr 12, 2026

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…

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Linux System Configuration

Alt-Tab Between Windows Only in GNOME
ByEric Ma Mar 24, 2018Apr 13, 2026

GNOME’s default Alt-Tab behavior switches between applications, grouping all windows from the same app together. If you work with multiple windows in a single application—multiple browser tabs, text editors, or terminals—this becomes frustrating. Here’s how to change it to window-based switching. Using the Alternate Tab Extension The simplest approach is enabling GNOME’s built-in Alternate Tab…

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Web Development

Responsive CSS Loading with Media Queries and @import
ByEric Ma Mar 24, 2018Apr 13, 2026

You can use @import with media queries to conditionally load CSS files only for specific viewport sizes. This is useful for loading layout-specific stylesheets, web fonts, or icon libraries only when needed. Basic Syntax The general format is: @import url(‘path/to/file.css’) media-query; The media query parameter controls when the stylesheet loads. Here are practical examples: /*…

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Linux System Configuration

Fix gthumb Hanging When USB Devices Are Connected
ByEric Ma Mar 24, 2018Apr 13, 2026

When gthumb hangs during startup after connecting an iPhone, external drive, or other USB device, the issue typically stems from gthumb attempting to enumerate mounted storage devices during initialization. Certain filesystem states, permissions misconfigurations, or slow I/O can cause the process to block indefinitely. Quick fix: unmount the device The most straightforward solution is to…

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Development Best Practices

dd on Windows: WSL2, Cygwin, and Native Alternatives
ByEric Ma Mar 24, 2018Apr 12, 2026

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…

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Development Best Practices

Installing Fedora on MBR Disks
ByEric Ma Mar 24, 2018Apr 12, 2026

If you’re working with legacy BIOS systems and MBR partition tables, Fedora’s installer can sometimes misdetect your firmware mode and attempt UEFI/GPT setup on hardware that only supports legacy BIOS. This guide covers the proper approach for Fedora 39+ on MBR systems. Prerequisites Before starting, verify your system configuration: Boot the installer in legacy BIOS…

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Linux System Configuration

Boot Windows from GRUB2 Command Line
ByEric Ma Mar 24, 2018Apr 13, 2026

If you need to boot Windows from the GRUB2 command line—whether during troubleshooting, recovery, or when your boot configuration is broken—you can do it with a few commands. This guide covers both BIOS and UEFI systems. Quick boot for BIOS systems Assuming Windows is installed on the first partition of the first disk in NTFS…

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Development Best Practices

Running Emacs in Terminal-Only Mode
ByEric Ma Mar 24, 2018Apr 13, 2026

If you want Emacs to run in the terminal without opening an X window, you have several practical options depending on your setup and workflow. Option 1: Install emacs-nox (Recommended for servers) The cleanest approach is installing the no-X variant of Emacs, which is built without X11 support. This reduces memory overhead and startup time…

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