Programming languages and software development
Filtering RSS feeds lets you reduce noise and focus on content that actually matters. Whether you want to exclude posts mentioning certain topics or only see items matching specific keywords, there are several practical approaches depending on your setup. Using dedicated feed filtering services Feed43 (https://www.feed43.com/) is one of the most reliable web-based tools for…
Logging connections that hit rate-limit rules helps you identify brute force attempts and troubleshoot legitimate clients that are being blocked. The standard approach is to create a dedicated chain that logs packets before dropping them. Create a logging and drop chain First, create a custom chain to handle logging and dropping: iptables -N LOGNDROP iptables…
Rate-limiting SSH brute-force attempts is essential for any server exposed to the internet. Using iptables with the recent module, you can drop connections from IPs that exceed a threshold in a given time window—for example, blocking IPs that attempt more than 6 connections in 60 seconds. Using iptables The recent module tracks connection attempts by…
ELPA (Emacs Lisp Package Archive) is the built-in package manager for Emacs. Keeping packages up to date is straightforward using the interactive package interface. Using the Package Menu Open the package list with: M-x list-packages This command displays all installed and available packages, and automatically refreshes the package archive contents. The buffer shows each package…
Xterm doesn’t send Alt key escape sequences by default, which breaks Alt-based keybindings in Vim, Emacs, shell readline, and other applications. Here’s how to fix it across different terminal setups. Xterm Configuration Add this to your ~/.Xresources file: xterm*metaSendsEscape: true Then load the changes and restart xterm: xrdb -merge ~/.Xresources xterm & This tells xterm…
When backing up with rsync, you often need to skip directories like cache/, node_modules/, or .git/ that appear at multiple levels in your directory tree. Listing every instance individually is impractical, but rsync’s exclude patterns handle this elegantly. Basic exclude syntax The simplest approach uses –exclude with a directory name pattern: rsync -avxP –exclude=cache/ /path/to/src/directory/…
When you create a new branch locally and try to git pull, you’ll hit this error if the branch doesn’t have upstream tracking configured: You asked me to pull without telling me which branch you want to merge with, and ‘branch.dev-harry.merge’ in your configuration file does not tell me, either. This happens because Git doesn’t…
A USB drive that’s mounted as read-only is frustrating — you can read files but can’t write, delete, or modify anything. This usually happens due to filesystem issues, hardware problems, or missing drivers. Check the Current State First, identify how the drive is mounted and what filesystem it uses: lsblk -f Look for your USB…
MPlayer is largely unmaintained as of 2026. For playing 3D movies on standard displays, mpv is the modern replacement and offers better stereo rendering support. Using mpv for 3D Playback The most straightforward approach with mpv is to use the stereo3d filter to convert side-by-side or other 3D formats to anaglyph (color-separated) stereo: mpv –vf=stereo3d=sbsl:arced…
fdisk -l displays partition information in sectors by default, which isn’t practical for most sysadmin tasks. While fdisk itself lacks options to change the unit display, parted shows partition sizes in GB/MB/KB automatically and is the better tool for this job. Using parted for readable partition output Run parted with the -l flag to list…
Spark SQL doesn’t have a separate DDL/DML specification distinct from Hive QL — it inherits its SQL dialect directly from Hive. If you’re designing a SQL engine or looking to understand Spark SQL’s data definition and manipulation capabilities, you need to reference Hive’s DDL and DML documentation. Why Spark SQL Uses Hive QL Spark SQL…
Database commands fall into distinct categories based on what they do. The two most fundamental are DDL (Data Definition Language) and DML (Data Manipulation Language). Understanding the difference is essential for anyone working with databases, from writing migrations to managing production systems. DDL: Data Definition Language DDL statements define and modify the structure of your…
When you need to change the commit message of a past commit that isn’t HEAD, git commit –amend alone won’t help. You’ll need to use interactive rebase to stop at that commit, amend it, and then continue. Interactive Rebase to Edit a Commit The core approach is git rebase -i with the commit hash. Say…
A sequence point is a point in execution where all side effects from previous evaluations are guaranteed to be complete and visible. Understanding sequence points is critical for writing correct C code, especially when dealing with expressions that modify variables. The C standard defines side effects as changes to the state of the execution environment…
A database schema is the blueprint that defines how data is organized and stored in a database. Think of it as the architectural plan for your database—it specifies tables, columns, data types, relationships, constraints, and rules that govern how data can be stored and accessed. Core Components of a Schema A schema encompasses several key…
Attaching storage to a running Xen DomU without rebooting is straightforward using the xl toolstack. This is useful when you need to add capacity, attach backup storage, or provision new volumes without downtime. Basic Disk Attachment To attach a logical volume or physical disk to a running DomU, use xl block-attach on Dom0: xl block-attach…
If you’re running Google AdSense on your site, you might want to show ads only to desktop visitors and hide them on mobile devices. This reduces clutter on smaller screens and can sometimes improve user experience—though test your bounce rates to confirm it actually helps your metrics. Using CSS Media Queries The cleanest approach is…
When you need to share work in progress or maintain a separate feature branch on a remote Git server, you’ll need to create a local branch and push it upstream. Here’s how to do it properly. Basic workflow The fundamental process involves three steps: Create a local branch and switch to it Make changes and…
When working with codebases that use non-standard file extensions for C source files, ctags won’t recognize them by default. You can configure it to treat files with custom extensions like .c0 or .puc as C source code. Using the langmap option The simplest approach is to add language mappings to your ctags configuration. Edit ~/.ctags…
When working with non-standard C file extensions, Vim’s taglist plugin and filetype detection won’t automatically recognize them. You need to explicitly tell Vim to treat those files as C source. Basic approach Add this to your ~/.vimrc: autocmd BufRead,BufNewFile *.c0 set filetype=c Replace *.c0 with whatever extension you’re using. This tells Vim that any file…