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,…
Locating Core .mli Files When you install Core via opam, the interface files (.mli) are stored in your OPAM switch directory. The exact path depends on your OCaml version and OPAM setup. Standard Location The .mli files for Core are located at: ~/.opam/$(OCAML_VERSION)/lib/core/ where $(OCAML_VERSION) is your installed OCaml version. For example, with OCaml 5.2:…
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…
Bootloader Stage1 Target Device Error During Fedora Installation This error occurs when Fedora’s Anaconda installer cannot properly configure the bootloader, typically when it encounters conflicts between EFI and legacy boot modes or when the partition table format doesn’t match the system firmware expectations. Root Cause The error “you have not created a bootloader stage1 target…
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…
PDF Annotation Tools on Linux Several native options now exist for annotating PDFs directly on Linux, though each has trade-offs between features and ease of use. Native Linux Tools Okular is the most straightforward choice for basic annotations. It’s lightweight, fast, and saves markups directly into the PDF: sudo apt install okular okular document.pdf Okular…
Installing WordPress on Fedora Install the required LAMP stack components. Fedora 41 and later use dnf instead of yum: sudo dnf install httpd php php-mysqli php-gd mariadb-server Note that php-mysql is deprecated; use php-mysqli instead for modern MySQL/MariaDB connections. Start and enable the services to run on boot: sudo systemctl start mariadb httpd sudo systemctl…
Repairing Database Tables Using Backups Database corruption happens. Whether it’s from unexpected shutdown, filesystem errors, or hardware issues, knowing how to recover from backups is essential sysadmin knowledge. When to Use Backups vs. Native Repair Tools Before jumping to restore from backup, consider your options: Native repair tools (REPAIR TABLE, CHECK TABLE) are faster and…
Fontconfig Warnings Breaking gnuplot and ps2epsi 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…
Trapping Ctrl-C in Bash Scripts Handling Ctrl-C gracefully in a Bash script is essential when you need to perform cleanup operations, save state, or notify users before exiting. The trap builtin makes this straightforward. Basic Trap Setup The fundamental approach uses the trap command to catch the INT signal (which Ctrl-C generates): trap ctrl_c INT…
Configuring Hadoop Mappers and Reducers for Optimal Performance Choosing the right number of mappers and reducers directly impacts Hadoop job performance. This isn’t a set-and-forget configuration—it depends on your cluster characteristics, data size, and task complexity. Mapper Configuration The number of mappers is primarily determined by the number of HDFS blocks in your input files….
Setting –no-print-directory in Makefiles 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….
Background processes in Bash Spawning background processes in Bash is straightforward with the & operator, but there are several nuances depending on your use case. Basic approach The simplest method is appending & to your command: for i in $(cat ./all-hosts); do ssh “$i” “ifconfig | grep Link” & done Each & launches the process…