If you’re seeing elevated TCP segment retransmission counts on Xen VMs, this typically signals network congestion, packet loss, or CPU contention. Here’s how to identify the root cause and fix it. Check Your Current Retransmission Rate Start by gathering baseline metrics: ss -s Look for the retransmit counters: TCP: established 45 tw 3 alloc 48…
Facebook operates two distinct caching systems, each designed for different access patterns and consistency requirements. Memcache serves as a lookaside cache where the intelligence resides primarily on the client side. This architecture means applications are responsible for cache invalidation, consistency checks, and determining what data to cache. Memcache is stateless and horizontally scalable, making it…
Scala runs on the JVM and combines object-oriented and functional programming. Here’s how to install Scala on Fedora Linux using several methods. Method 1: Install via Coursier (Recommended) Coursier is the official Scala installer and handles JDK dependencies automatically: # Install Coursier curl -fL https://github.com/coursier/coursier/releases/latest/download/cs-x86_64-pc-linux.gz | gzip -d > cs && chmod +x cs &&…
You’ll sometimes need to exclude specific repositories from package operations—typically when multiple repos provide the same package, mirror connectivity is unreliable, or you want to force installation from a trusted source. The –disablerepo flag lets you skip repos on a per-command basis. Basic syntax dnf –disablerepo=repoid1 –disablerepo=repoid2 install package-name Add –disablerepo once for each repo…
When your distro’s package repositories lag behind, installing Scala directly from the official release is straightforward. This approach works on any Linux system with Java already installed. Prerequisites You’ll need a JDK installed. On most systems: # Debian/Ubuntu apt install default-jdk # RHEL/Fedora/CentOS dnf install java-17-openjdk-devel # Alpine apk add openjdk17 Verify your Java installation:…
To generate native assembly code (x86-64 asm, ARM64, etc.) from OCaml’s native compiler, use the -S flag along with other optimization-related options: ocamlopt -S -inline 20 -nodynlink not.ml -o not.opt This produces a .s file containing the generated assembly. The flags break down as: -S — Stop after assembly generation and keep the .s file…
If you need to clean up spam content across your MyBB forum quickly, the Goodbye Spammer plugin automates the process of banning a user and removing all their content in one operation. Installation Download the Goodbye Spammer plugin from the MyBB Mods site, then: Upload ./inc/plugins/goodbyespammer.php to ./inc/plugins/ Upload ./inc/languages/english/goodbyespammer.lang.php to ./inc/languages/english/ Navigate to ACP…
Question2Answer’s RSS feed configuration includes a toggle for “Include full text in feeds” but offers no built-in option to display excerpts instead of full content. If you need excerpt functionality, you’ll need to modify the feed generation code. This approach works with Question2Answer 1.5.4+. The method involves creating a custom feed handler that truncates content…
When you pipe a plain text file to mailx, it analyzes the content to determine the MIME type. If it detects non-standard characters (anything other than newlines and horizontal tabs), it defaults to application/octet-stream and base64-encodes the message. Most email clients then treat this as an attachment rather than inline content. This is the problematic…
Linux routing tables exist in kernel memory during runtime. To persist routes across reboots, you need to store them on disk and have them reloaded during system startup. The mechanism varies depending on your network management setup. systemd-networkd and netplan (modern systems) On contemporary distributions using systemd-networkd or netplan, define routes in YAML configuration files….
A MySQL table marked as crashed typically occurs after unclean shutdowns, power failures, or server crashes. Error 145 indicates the table structure is corrupted and needs repair before queries can proceed. Checking Table Status Before attempting repair, check the table status: CHECK TABLE mybb_sessions; This returns detailed information about corruption. Common status values: OK —…
Converting Word documents to PDF is a fundamental task in most workflows. Modern versions of Office have native PDF export built in, but understanding your options and potential gotchas will save you time. Native PDF Export (Modern Office) If you’re using Office 2010 or later, PDF export is built into the application—no add-ons required. Open…
You can run OCaml scripts directly from the command line with a shebang, similar to bash or Python. This requires making the file executable and using the proper interpreter directive. Basic Script Setup Create a file with a .ml extension and add a shebang at the top: #!/usr/bin/env ocaml print_endline “Hello world!”;; Then make it…
Local branches List all branches on your local repository: git branch This shows only branches that exist locally on your machine. Remote branches To list all branches on the remote server, use the -r flag: git branch -r This displays remote-tracking branches — local references to branches that exist on the remote repository. These are…
Y-axis labels in Gnuplot can end up positioned awkwardly depending on your terminal, font, and tick label width. The most straightforward solution is using the offset option in the set ylabel command. Basic Offset Syntax The offset takes three parameters: horizontal, vertical, and depth (for 3D plots): set ylabel “Y Label” offset <x_offset>,<y_offset>,<z_offset> Positive values…
iTunes backups are stored in device-specific directories. The location depends on your operating system: macOS: ~/Library/Application Support/MobileSync/Backup/ Windows: %APPDATA%\Apple Computer\MobileSync\Backup\ On Windows, the easiest way to navigate there is to press Win + R, type %appdata% and hit Enter, then navigate to Apple Computer\MobileSync\Backup\. Understanding iTunes Backup Files iTunes stores backups as a collection of…
Copying webpage content directly into a document often produces poor formatting, missing images, or broken layouts. Here are several practical approaches to get clean, readable output. Browser Print Dialog (Native) Most modern browsers have built-in print functionality that’s worth trying first: Open the page in your browser Press Ctrl+P (Linux/Windows) or Cmd+P (macOS) In the…
Modern Fedora systems keep multiple kernel versions available, but older kernels are tucked in a submenu rather than appearing as top-level GRUB2 entries. This requires a slightly different approach when setting them as your default boot option. Understanding the GRUB2 submenu structure When you run: grep menuentry /boot/grub2/grub.cfg | cut -d “‘” -f2 You’ll see…
If you use both the Chrome RSS Subscription Extension and Feedly, you can integrate them so that clicking the RSS icon in your browser automatically opens your feed in Feedly instead of the browser’s default handler. Understanding the Integration When you subscribe to an RSS feed through the Chrome extension, it needs a target URL…
Font sizes in Gnuplot plots often appear too small when scaling images down for papers or presentations. You can control font sizes at multiple levels: globally for the terminal, for axis labels and tick marks, for legends, and for individual text elements. Global Terminal Font Size Set a default font and size for your entire…