Booting Fedora with an older kernel in GRUB2 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…
Package Management Tools for OCaml Managing OCaml packages effectively depends on your workflow and environment. The current standard is OPAM (OCaml Package Manager), which handles dependency resolution, version switching, and sandboxed environments. OPAM: The Standard Choice OPAM is the de facto package manager for OCaml and is maintained by the OCaml community. Install it using…
Loading source files into the OCaml toplevel To load and execute code from a source file in the OCaml interactive toplevel, use the #use directive: #use “file-name”;; This reads, compiles, and executes OCaml phrases from the specified file as if you’d typed them directly into the toplevel. Execution stops at the first error encountered. Common…
cin Performance vs scanf 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…
Calling C Functions from OCaml OCaml provides robust FFI (Foreign Function Interface) capabilities for calling C code. This is essential when you need to use existing C libraries or write performance-critical sections in C. Using the Unix Module The simplest approach for Unix/Linux system calls is the built-in Unix module, which wraps common POSIX functions…
Understanding OCaml Integer Size 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…
Which ones are good systems conferences? Top ones by ACM and USENIX: OSDI: https://www.usenix.org/conferences/byname/179 SOSP: http://sosp.org/ Other SIGOPS Events: http://www.sigops.org/conf-sponsored.html EuroSys: http://www.eurosys.org/ SoCC: http://www.socc2013.org/ (SoCC 2013) ASPLOS: http://www.sigplan.org/Conferences/ASPLOS/Main VEE: http://www.sigplan.org/vee.htm USENIX ATC: https://www.usenix.org/conferences/byname/131 NSDI: https://www.usenix.org/conferences/byname/178 IEEE Conferences: ICDCS: http://www.temple.edu/cis/icdcs2013/ (2013) IPDPS: http://www.ipdps.org/ Other related ones and workshops: HPCA: Search HPCA ConferenceSC: http://www.supercomp.org/IEEE CLUSTER: http://www.clustercomp.org/ HotCloud:…
Transactional Memory Learning Materials Transactional memory (TM) is a synchronization mechanism that simplifies concurrent programming by allowing multiple threads to execute code atomically without explicit lock management. If you’re getting into this area, here are the best resources and practical approaches to build solid understanding. Foundational Reading The classic reference is still Transactional Memory by…
Consistency Models in Distributed Systems 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…
Setting Chrome proxy settings from the command line on Linux Chrome supports proxy configuration via command-line flags, which is useful for scripting, automation, or testing without touching the GUI settings. This works across all major Linux distributions. Basic proxy configuration Use the –proxy-server flag when launching Chrome: google-chrome –proxy-server=”socks://localhost:8080″ Proxy scheme formats The proxy specification…
Syncing iPhone Contacts with Google Gmail The most reliable way to keep your iPhone contacts synchronized with Google is through CardDAV, Google’s contact synchronization protocol. This works on modern iOS versions and automatically syncs changes in both directions. Using Native iOS CardDAV Setup Navigate to Settings > Mail > Accounts > Add Account: Select Other…
Adding Google Custom Search to Question2Answer If you’re running Question2Answer and want to replace the default search with Google Custom Search without modifying your theme, a plugin is the cleanest approach. Setup Requirements Before implementing Google Custom Search, you’ll need: A Google account Google Custom Search Engine (CSE) created at cse.google.com Your CSE ID (cx…
Restoring GNOME Session State GNOME can automatically restore your session—reopening all applications and windows that were running when you last logged out. This differs from autostart scripts, which launch specific programs on every login regardless of what was running before. Automatic Session Restoration To enable automatic session restoration in GNOME: Open Settings → General (or…
Restarting GNOME without closing running applications If you need to restart GNOME while keeping your applications open, you have several options depending on your GNOME version and setup. Quick restart with Alt+F2 The fastest method is to use GNOME’s run dialog: Press Alt + F2 Type r and press Enter This restarts the GNOME shell…
Popular NoSQL Databases in 2026 NoSQL databases have matured considerably and now handle a significant portion of production workloads. The landscape has shifted toward specialized solutions rather than one-size-fits-all approaches. Here’s a breakdown of the most widely deployed options: Document Stores MongoDB remains the most popular document database. It’s production-ready, well-documented, and offers strong consistency…
Using the OCaml Toplevel with Readline Support The default OCaml toplevel lacks basic readline features like history, line editing, and command completion. Here are the practical approaches to fix this. utop: Full-Featured Replacement The best option for daily interactive OCaml work is utop, a replacement toplevel that provides: Syntax highlighting with color output Command completion…
Using Your iPhone as a Wireless Mouse on Linux Your iPhone’s touchscreen can serve as a remote input device for your Linux desktop or laptop. Here are the most practical approaches. WiFi Mouse Method The WiFi Mouse application lets you control your Linux system’s cursor and clicks from your iPhone over a local network. Setup:…
Converting and installing .deb packages on Fedora Fedora uses RPM packages managed by DNF, but you’ll occasionally encounter software distributed only as .deb files (Debian format). You have several options: convert the .deb to RPM, extract and repackage it, or use containerization. Here’s what works in practice. Using alien to convert .deb to RPM The…
Finding Photo Timestamps on iPhone iPhone’s Photos app doesn’t display EXIF metadata by default, but the timestamp information is embedded in every photo. You need to access the EXIF data to see when a photo was actually taken. Using the Photos App (Built-in) Starting with iOS 15+, Apple added some native EXIF viewing directly in…
SQL Layers on NoSQL Databases 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…