Tracing Functions in OCaml The #trace directive in OCaml’s interactive toplevel (ocaml or utop) logs function calls and returns, showing you exactly what arguments go in and what values come back out. This is invaluable for debugging recursive functions and understanding execution flow. Basic Usage Define a function and enable tracing with #trace: # let…
Using nm to inspect static library symbols The nm command displays symbolic information from object files, libraries, and executables. It’s the standard tool for inspecting what functions and variables are defined or referenced in a static library (.a file). Basic usage List all symbols in a library: nm lib.a This outputs symbol names, but the…
Mounting Ext4 Partitions in Windows Accessing Linux filesystems from Windows is useful when dual-booting, migrating data, or recovering files. Read-only access is essential to prevent accidental corruption of ext4 metadata and data. Why Read-Only Access Matters Ext4 is designed for Linux environments. Windows drivers lack complete understanding of ext4 journaling, extended attributes, and other advanced…
Remove cookies for a specific site in Chrome You can delete cookies from individual sites without clearing your entire browser cache. Here’s how: Via Settings UI Open chrome://settings/privacy in the address bar (or go to Settings > Privacy and security) Click Cookies and other site data Click All cookies and site data Use the search…
Generating Random Strings in Bash There are several reliable methods to generate random strings of a specific length in bash. The choice depends on your character set requirements and use case. Using tr with /dev/urandom The tr command combined with /dev/urandom is the most portable and straightforward approach: tr -dc “[:alpha:]” < /dev/urandom | head…
Resetting the Disqus WordPress Plugin Installation If you’ve deactivated and reactivated the Disqus WordPress plugin but it’s still using the old forum ID and configuration, you need to clear the stored settings from your database. This is the most reliable way to force the plugin to re-initialize and prompt you for fresh configuration. Why This…
Automatically Filling PDF Forms with Batch Data When you need to populate PDF forms with large datasets, manual entry becomes impractical. Scripting this process saves time and eliminates human error. Here’s how to automate PDF form filling using Python. Understanding PDF Form Filling PDF forms contain field names that can be programmatically populated. The process…
Installing WordPress in a Subdirectory While Serving From Root Installing WordPress in a subdirectory keeps your site root cleaner and makes it easier to manage core files separately from content. Here’s how to configure WordPress so the admin and core files live in /wordpress while the site appears at your domain root. Creating the Subdirectory…
PuTTY profiles and sessions on Windows PuTTY stores all SSH session configurations in the Windows registry under HKEY_CURRENT_USER\Software\SimonTatham\PuTTY. This includes hostnames, connection settings, terminal preferences, and authentication keys. Exporting PuTTY settings To back up or migrate your PuTTY profiles to another machine: Open Registry Editor by pressing Win+R and typing regedit Navigate to HKEY_CURRENT_USER\Software\SimonTatham Right-click…
Setting up MySQL replication MySQL replication lets you maintain synchronized copies of your database across multiple servers. This is essential for high availability, read scaling, and backups. Here’s how to configure it properly. Prerequisites You need at least two MySQL instances: a primary (source) and one or more replicas. Both should run the same or…
Moving Domain Hosting Between Dreamhost Accounts If you’re trying to add a domain to a Dreamhost account and get the error “You can’t add that domain: already in our system,” the domain is already configured for DNS hosting in another Dreamhost account. You need to remove the DNS hosting from the original account before you…
Changing an Attachment’s Parent Post in WordPress Attachments in WordPress are tied to specific posts through a parent-child relationship stored in the database. This matters more than you’d think — attachment metadata, URLs, and admin filtering all depend on that parent assignment. Sometimes you need to reassign an image or document to a different post,…
Secure Email: Practical Approaches Sending sensitive information via email requires careful consideration. Whether you’re sharing financial details, credentials, or confidential documents, there’s no single “secure email” solution that eliminates all risk — you need to match the method to your threat model. Understand the Risk Standard email transmits in plaintext across multiple servers. Even with…
Adding the Jane Street OPAM Repository The Jane Street OPAM repository contains specialized OCaml packages and libraries maintained by Jane Street, including their popular Core library and related tools. You’ll need to add this repository to your OPAM configuration to access these packages. Method 1: Clone and Add Locally If you prefer to clone the…
Importing OCaml Libraries The OCaml compiler only finds the standard library (List, Array, etc.) by default. Third-party libraries require you to explicitly tell the compiler where to find them. Using ocamlfind The standard approach is ocamlfind, a package manager that tracks installed libraries and their locations. It’s part of the OPAM ecosystem and should already…
Finding CPU Core Count on Linux Determining the number of CPU cores available on a Linux system is essential for performance tuning, application configuration, and capacity planning. Several approaches exist depending on what information you need. Quick check: nproc The simplest way to get the number of CPU cores is nproc: $ nproc 8 This…
Finding the Storage Engine of a Table To check which storage engine a table uses, query the information_schema database: SELECT ENGINE FROM information_schema.TABLES WHERE TABLE_SCHEMA = ‘database_name’ AND TABLE_NAME = ‘table_name’; Replace database_name and table_name with your actual values. You can also use the SHOW TABLE STATUS command for a quicker view: SHOW TABLE STATUS…
Changing PHP Memory and Execution Time Limits You’re seeing fatal errors because PHP has hit its default resource constraints: PHP Fatal error: Maximum execution time of 30 seconds exceeded PHP Fatal error: Allowed memory size of 268435456 bytes exhausted These limits exist to prevent runaway scripts from consuming server resources. Here’s how to increase them….
Replacing Strings in MySQL Tables To replace strings across one or more columns in MySQL tables, use the REPLACE() function with an UPDATE statement. This is useful when migrating domains, fixing URLs, updating API endpoints, or correcting data patterns at scale. Basic Syntax UPDATE table_name SET column_name = REPLACE(column_name, ‘old_string’, ‘new_string’) WHERE column_name LIKE ‘%old_string%’;…
Setting Up HP Printers on Fedora Linux HP printers work well on Fedora when you install the right packages and drivers. Here’s what you need to do to get a USB or network-connected HP printer working reliably. Install HPLIP and Related Packages Start by installing the HP Linux Imaging and Printing (HPLIP) suite: sudo dnf…