OS File Extensions on Linux by Libor Benes (Dr. B)

OS File Extensions on Linux turns a mystery file extension into a clear, one-line answer — straight from a bundled reference table, not a search engine or an external lookup service.

See at a glance what a Linux-related extension actually is: type its name or a keyword into the search box, or pick from 14 categories, and a card appears showing its common name, its category, and where it sits and what it does inside the Linux file system — from .service systemd units to .ko kernel modules to .desktop application entries, plus device nodes, pipes, and sockets that Linux identifies by type rather than by suffix.

Built for anyone who has ever stared at an unfamiliar extension and wondered whether it was safe, important, or junk — IT technicians triaging unfamiliar files, students learning how Linux internals fit together, and anyone who likes a quick, reliable answer close at hand.

🏛 About OS File Extensions on Linux:
• Linux accumulates a wide spread of file extensions over time, but only a small, definable subset belongs to the OS itself — its kernel, its service manager, its packaging tools, its shell, and its device layer.
• OS File Extensions on Linux isolates that subset and explains each entry in one line, without judging, scanning, or touching any file on your actual disk.

📐 Desktop Sidebar Design:
🔎 Search Box: Type an extension, keyword, or category term; the list filters live.
🏷 Category Filter: Narrow results to one of 14 curated categories.
📇 Entry Cards: Extension, category tag, common name, and a one-line explanation per result.
📋 Copy Button: One click copies the extension text to the clipboard.

⚙ How It Works — Static Data, Nothing Sent Anywhere:
• All 106 entries are bundled with the extension as hand-authored reference data; nothing is fetched, scraped, or downloaded at run time.
• Search and filtering happen entirely client-side against the bundled data.
• Search input is sanitized to a restricted character set and capped in length before use.
• Every row and label is built with safe, text-only DOM methods — nothing is ever inserted as HTML.

📚 Extension Coverage:
There is no official, closed registry of "all Linux OS file extensions," and the boundary is genuinely fuzzy rather than merely incomplete — some extensions are shared with other platforms, some are POSIX-defined formats mostly used by third-party software, and some are legitimately borderline. Some of Linux's most OS-defining files — device nodes, sockets, named pipes — carry no dot-extension at all, so they're covered under a dedicated Special category keyed to the same type codes shown by ls -l. This add-on does not claim to list "all" Linux extensions; it lists a defensible, consensus-level set of 106 extensions and special file types that most people would agree belong to Linux' core system, scripting, configuration, boot, packaging, service-management, and kernel layer, organized into 14 explicit categories so the scope is stated, not implied.

📊 What You See:
📇 Entry Card: Extension, category tag, common name, and a one-line explanation per result.
🔎 Live Count: Matching entries out of the full 106, updated as you type or filter.
✨ Bright, High-Contrast Theme: Neon accents on a dark background, built for quick scanning.

🖥 Features:
🔎 Live Search — Filters by extension, name, description, or category as you type.
🏷 Category Filter — Jump straight to one of 14 curated categories.
🧾 Curated Descriptions — 106 hand-written entries, each naming a location and purpose.
📋 One-Click Copy — Copies any extension's text to the clipboard.
🪶 Zero Overhead — Five small files; nothing runs while the sidebar is closed.
🔒 Client-Side Only — All search, filtering, and rendering happen entirely in your browser.

🎯 Perfect for:
• Anyone who finds an unfamiliar extension on a Linux machine and wants a quick answer.
• IT support staff and technicians triaging unfamiliar files during troubleshooting.
• Students and hobbyists learning how the Linux file system and OS internals fit together.

🔒 Security-First Architecture:
✅ No Data Collection — Explicitly declared in manifest.json.
✅ No Telemetry — No analytics, no tracking, no third-party requests of any kind.
✅ No eval() or innerHTML — Every row and label is built with safe, text-only DOM methods.
✅ Validated Input — Search text is sanitized to a restricted character set and length before use.
✅ Minimal, Purpose-Bound Permissions — The single permission requested (clipboardWrite) maps directly to the Copy button and nothing else.
✅ Flat, Auditable Codebase — Five files total: manifest, sidebar HTML, stylesheet, sidebar script, and extension-data file.

🛠 Technical Details:
• Compatibility: Firefox 140.0+ Desktop only.
• Runtime Execution RAM Footprint: ~27 KB (core scripts: manifest.json + sidebar.html + style.css + script.js + data.js).
• Total Extension Download/Install Size: ~64 KB (including README.md).
• Total Extension .zip Compressed Size: ~22 KB (including README.md).
• Entry point: sidebar_action panel (sidebar.html).
• Network requests: None. The extension never initiates or observes any network activity.
• Storage: None. All data is static and bundled; nothing is written to disk or synced.
• Permissions requested: clipboardWrite (for the Copy button only).
• Data Collection: None (explicitly declared).

⚠ Limitations:
📚 Curated, Not Exhaustive — See Extension Coverage above for exactly what is included and why a complete list of "all Linux extensions" isn't a well-defined target.
🖥 Desktop Only — Firefox sidebars are not available on Android.
🧊 Static Data — Reflects a point-in-time curation; new distro tooling or kernel features may introduce extensions not yet covered here.
🕵 Not a File Identifier — Matches only against its own bundled reference table; it does not inspect, scan, or identify files on your actual disk.

⚠ Legal Disclaimer:
OS File Extensions on Linux is an independent, informational browser extension, not affiliated with, endorsed by, or sponsored by Linus Torvalds, the Linux Foundation, or any Linux distribution vendor. "Linux" and related names are trademarks of their respective owners and are used here only for descriptive purposes.