If gnuplot or ps2epsi fails to run or produces excessive warnings on modern Fedora systems, you’re likely hitting a fontconfig deprecation issue. The symptom is repeated warnings like: Fontconfig warning: “/etc/fonts/conf.d/50-user.conf”, line 14: reading configurations from ~/.fonts.conf is deprecated. This happens because /etc/fonts/conf.d/50-user.conf still includes a deprecated reference to ~/.fonts.conf. While the warning alone doesn’t…
The –no-print-directory flag suppresses make’s default behavior of printing messages when entering and leaving subdirectories. If you invoke make frequently with recursive calls or have a deeply nested project structure, these messages clutter your output. Rather than passing the flag on every invocation, you can set it once in your Makefile. Add this line near…
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 &&…
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…
The common claim that cin is significantly slower than scanf in C++ is partially true, but only when comparing default configurations. The reality is more nuanced. Why cin Can Be Slower by Default By default, C++ streams maintain synchronization with C stdio streams (stdin, stdout, stderr). This synchronization requires additional overhead because the library must…
OCaml’s int type size depends on your platform’s architecture. On 64-bit systems, int is 63 bits; on 32-bit systems, it’s 31 bits. This catches many people off guard when they test bitwise operations. Here’s why: OCaml uses one bit as a tag to distinguish integers from pointers at runtime (the least significant bit). So on…
Consistency models define the guarantees that a distributed system makes about the order and visibility of data modifications across nodes. Understanding these models is essential when designing systems, choosing databases, or debugging data anomalies in production. Strong Consistency Models Strict Consistency is the ideal but rarely achievable model. It guarantees that reads always reflect the…
SQL layers abstract traditional relational query interfaces over distributed NoSQL and big data systems, enabling applications to leverage SQL’s familiarity while benefiting from horizontal scalability. Here are the key approaches and systems that have emerged in this space. Distributed SQL on Key-Value Stores Phoenix (Apache Phoenix) provides a SQL interface over HBase. It compiles SQL…
Use usermod to add a user to supplementary groups. The -a (append) flag is critical — without it, you’ll remove the user from all groups not explicitly listed. usermod -a -G group_name user_name To add a user to multiple groups at once: usermod -a -G group1,group2,group3 user_name Options explained -a, –append Append the user to…
In many WordPress themes, the sidebar loads before the main content area in the HTML source. This affects SEO and accessibility, since search engines and screen readers process content in source order. Moving the main content div before the sidebar in HTML while keeping the visual layout intact improves your site’s structure. The Problem A…
If you follow accounts but they don’t follow you back, you’ll want a reliable way to identify those one-sided relationships. Here’s how to approach it in 2026. Native X/Twitter Tools X’s official analytics and settings have evolved. While the platform doesn’t provide a built-in “find non-followers” feature in the main UI, you can use: Through…
The default Vim plugin directory structure under ~/.vim is inherently messy. Without a plugin manager, files from different plugins scatter across autoload/, plugin/, ftplugin/, colors/, and other directories, making it difficult to track which files belong to which plugin. Removing a plugin requires manually hunting down and deleting its files across multiple locations. Several plugin…
Directory listing exposes your file structure to visitors and can be a security concern. Apache’s .htaccess file provides a straightforward way to disable this behavior while still allowing direct file access. Basic Implementation Create a .htaccess file in the directory where you want to disable listing: Options -Indexes Place this file in the root directory…
The caption LaTeX package provides customizable captions for floats (figures, tables, and other environments). It offers much more control than LaTeX’s default caption formatting. Install on Fedora The caption package is included in the texlive collection: # Install the full texlive collection (includes caption) sudo dnf install texlive-collection-latexrecommended # Or install just the caption package…
Linux can manage multiple swap partitions or files simultaneously, each with an assigned priority. The kernel allocates swap pages from highest to lowest priority, with round-robin allocation among equally-prioritized areas. Setting Swap Priority with swapon Use the swapon command to activate a swap partition and set its priority: swapon -p 10 /dev/sdc1 The -p flag…
There are several ways to determine a file’s size in C, each with different trade-offs. Choose based on whether you have a file descriptor, stream, or just the filename. Using stat() with a Filename If you know the filename, stat() is the most straightforward approach: #include <sys/stat.h> #include <stdio.h> int main(const char *filename) { struct…
When managing many systems, manually confirming host keys for each new connection gets tedious fast. You can configure SSH to automatically add unknown hosts to ~/.ssh/known_hosts without prompting. The Risk Trade-off Before implementing this, understand what you’re doing: disabling strict host key checking opens you to man-in-the-middle attacks. Only use this in trusted networks where…
Pasting external code into Vim often triggers unwanted autoindent behavior, adding extra indentation and breaking formatting. Vim’s paste mode disables all automatic indentation while inserting text, letting you paste code exactly as-is. Quick paste mode toggle Enable paste mode before pasting: :set paste Then paste your code. When done, disable it: :set nopaste This works,…