Programming languages and software development
YARN (Yet Another Resource Negotiator) fundamentally restructured Hadoop 2.0 by decoupling resource management from application logic. If you’re transitioning from Hadoop 1.x or building systems on top of YARN, understanding its architecture is essential for effective cluster administration and application development. Essential Reading The foundational paper Start with “Apache Hadoop YARN: Yet Another Resource Negotiator”…
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…
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….
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:…
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…
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…
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…
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 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…
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: /*…
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…
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…
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…
When you need to identify which package installed a command on your Fedora system, you have several reliable methods depending on whether the package is already installed. Quick lookup for installed commands The fastest approach combines which to locate the command with rpm to query the owning package: $ rpm -qf $(which ping) iputils-8.40-4.fc40.x86_64 The…
For any current Windows system, netsh winhttp is the standard command-line tool for proxy configuration. WinHTTP handles system-level proxy settings used by Windows Update, built-in applications, and services that don’t rely on browser-specific configuration. Set a proxy with bypass list netsh winhttp set proxy proxy-server=”proxy.example.com:8080″ bypass-list=”localhost;127.0.0.1;*.internal.local” Use semicolons to separate multiple proxy servers or bypass…
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…
Fedora upgrades are straightforward with dnf system-upgrade, the standard tool for network-based distribution upgrades. This replaces the older fedup tool and handles everything from downloading packages to managing the upgrade environment. Pre-Upgrade Checklist Before starting any upgrade: Update your current system: sudo dnf upgrade Back up critical data — especially /etc, home directories, and application…
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…
Fedora uses FirewallD as its default firewall management service. If you’re running servers in a trusted internal cluster or isolated environment where network-level filtering isn’t needed, you can disable it entirely. Stop and Disable FirewallD To completely disable the firewall: sudo systemctl stop firewalld sudo systemctl disable firewalld The stop command halts the service immediately….
If you need direct control over your firewall rules, you can disable firewalld and use iptables instead. This guide covers the setup process and best practices for maintaining persistent rules. Stop and disable firewalld If firewalld is currently running, stop it and prevent it from starting on boot: sudo systemctl stop firewalld sudo systemctl disable…