The nl command is purpose-built for adding line numbers to text files: nl text-file By default, nl numbers all non-empty lines and skips blank lines. This behavior is controlled by the body section style, which defaults to t (text only). Common nl options Number all lines including blanks: nl -ba text-file Start numbering at a…
You’ve accidentally broken a file and need to restore it from an earlier commit without touching anything else in your repository. Here’s how. Restore a file to a specific commit To restore my_file.name to its state at a specific commit: git checkout commit_sha1 my_file.name Replace commit_sha1 with the actual commit hash. You can find it…
Trailing spaces and tabs at the end of lines are common annoyances in source code and configuration files. They’re invisible, waste space, and can cause issues with certain tools or version control systems. Here’s how to remove them efficiently. Using sed The most straightforward approach with sed: sed ‘s/[[:space:]]*$//’ your_file > your_file.tmp && mv your_file.tmp…
WordPress Twenty Thirteen theme shows full post content on archive pages by default. Using excerpts instead keeps archive pages clean and improves page load speed by showing just a summary of each post. Enable Excerpts on Archive Pages Add this to your theme’s functions.php or a custom plugin: function twentythirteen_excerpts_on_archives($content) { if (is_archive() || is_home())…
Question2Answer’s RSS feed configuration includes a toggle for “Include full text in feeds” but offers no built-in option to display excerpts instead of full content. If you need excerpt functionality, you’ll need to modify the feed generation code. This approach works with Question2Answer 1.5.4+. The method involves creating a custom feed handler that truncates content…
If you’re working with Mingle Forum and need to remove canonical links from forum pages while preserving them elsewhere, you’ll need to locate the specific code in your theme’s class file. Finding the Code Reference The line numbers (like -1260) in a diff refer to specific locations within the file being modified. In this case,…
If you’ve made changes to your working copy but haven’t committed them yet, you can discard them using svn revert. This is useful when you want to abandon edits and go back to the last committed version. Basic Revert To revert all changes in your working copy, run this from the repository root: svn revert…
WordPress has included automatic canonical URL generation since version 2.9. While this is usually beneficial for SEO, certain scenarios require disabling it — for example, when forum plugins generate incorrect canonical URLs that point all threads to a single page. The Problem Canonical URLs tell search engines which version of a page is authoritative. When…
Archiving or copying a 1TB sparse file containing only 32MB of actual data is impractical with naive approaches—you’ll waste time and I/O bandwidth copying zeros. The solution is using SEEK_HOLE and SEEK_DATA flags with lseek(), which allow tools to skip over hole regions entirely. How SEEK_HOLE and SEEK_DATA work The Linux kernel provides two additional…
When you need to debug kernel behavior without full instrumentation frameworks, module parameters offer a pragmatic shortcut. Rather than immediately reaching for perf, kprobes, or eBPF, you can add simple toggles and state tracking directly in the code you’re investigating, then control them at runtime through sysfs. Frameworks like perf, kprobes, and eBPF are powerful…
git merge and git rebase both integrate changes from one branch into another, but they handle history differently. Merge creates a new commit that ties together the histories of both branches. Your feature branch history remains intact, and the main branch gains a merge commit. This is safer for shared branches because it doesn’t rewrite…
GNOME’s default Settings app doesn’t expose comprehensive font options, but GNOME Tweaks and command-line tools give you full control over typefaces across the desktop, shell, and window decorations. Installing GNOME Tweaks GNOME Tweaks is the easiest way to customize fonts. Install it on your system: Fedora: sudo dnf install gnome-tweaks Debian/Ubuntu: sudo apt install gnome-tweaks…
Sending email notifications when commits are pushed to a central Git repository helps teams stay coordinated and maintains audit trails. This is handled through Git hooks—scripts triggered by repository events. How Post-Receive Hooks Work When a client pushes to your Git server, the post-receive hook executes automatically. This hook lives at GIT_DIR/hooks/post-receive in your bare…
The diff utility generates unified diffs that show changes between file versions. Always use the -u flag to create unified diffs, which are the standard format for patches. For a single file: diff -u original.c new.c > fix.patch For an entire directory tree: diff -rupN original/ new/ > patchfile.patch The flags break down as: -r:…
Every user working with Git needs an SSH key pair for authentication. Generate one if you don’t have it: ssh-keygen -t ed25519 -C “your-email@example.com” Ed25519 keys are preferred over RSA for better security and performance. The command creates ~/.ssh/id_ed25519 (private key) and ~/.ssh/id_ed25519.pub (public key). Share the public key with your Git server administrator to…
Mistakes happen during development. Git provides several commands to undo changes at different stages—before committing, after committing, or in specific files. Understanding which tool to use depends on where you are in the workflow. Revert the entire working tree before committing If you’ve made changes to multiple files and want to discard everything back to…
ISO images are sector-by-sector copies of optical media stored as binary files. They’re useful for archiving DVDs or creating portable copies without keeping physical disks around. On Linux, several tools can accomplish this—dd is the simplest, but modern alternatives offer better features. Using dd to Create an ISO Image The most straightforward approach uses dd:…
Hadoop 1.x reached end-of-life in 2014 and is no longer maintained. This post documents a deprecated architecture for historical reference only. For new deployments, use Hadoop 3.x+ with YARN, which offers significant improvements in resource management, multi-tenancy, and reliability. See the Apache Hadoop documentation for current versions. For managed services, consider AWS EMR, Google Dataproc,…