IdeaWell

Project ideas from Hacker News discussions.

cp: -r or -R?

Original Article

Hacker News Discussion

📝 Discussion Summary (Click to expand)

Three prevalent themes in the discussion

  1. Inconsistencies of cp recursive flags (-r vs -R) across Unix‑like systems
  2. “Historic versions of the cp utility had an -r option. This implementation supports that option; however, its use is strongly discouraged, as it does not correctly copy special files, symbolic links or FIFOs.” – bariumbitmap (quoting the OpenBSD manual)

  3. “There are implementations of cp out in the wild that do not recognise the --recursive flag. OpenBSD was mentioned in the article and there’s also busybox cp.” – olowe

  4. Preference for rsync over cp and the nuances of its flags

  5. “I really like this feature of rsync (trailing '/' means copy the directory contents to the dest, no trailing '/' means copy the directory itself). Other tools, like cp, don't have any way at all to say copy the directory contents to the dest… ” – GrantMoyer

  6. “just use rsync” – emmelaich, pasc1878, and others

  7. Localization/trademark details of the Pokémon name (accent é) and the spelling “ditto”

  8. “Pokémon is the trademark … Pokemon is common spelling in countries where keyboards don't have é and/or where people aren't used to inputting é.” – amenghra
  9. “It's 'ditto', not 'dito'” – bsoqk

🚀 Project Ideas

Generating project ideas…

cpx – Cross‑Platform Copy Utility

Summary

  • A drop‑in replacement for cp that transparently maps -r/-R flags to the correct behavior on Linux, *BSD, macOS, and provides --reflink/copy‑on‑write when available.
  • Core value: users get consistent, safe recursive copying without memorizing platform‑specific quirks.

Details

Key Value
Target Audience Developers, sysadmins, and power users who frequently copy files across heterogeneous Unix‑like systems
Core Feature Unified flag interface (-r = recursive, -R = recursive with special‑file handling) that internally selects the appropriate system call or falls back to rsync/cp --reflink
Tech Stack Rust (for performance and safe syscalls), clap for CLI, libffi to query platform capabilities, optional librsync
Difficulty Medium
Monetization Revenue-ready: "Freemium – free CLI, paid team‑wide telemetry & policy dashboard ($9/user/mo)"

Notes

  • HN commenters lamented “the weird history and evolution of a tool that leads us to the rather odd situation that we are in today” (JdeBP) and wished for a tool that “just works” across platforms (dotancohen, alwillis).
  • Could spark discussion about standardizing copy semantics and reduce copy‑related bugs in scripts and CI pipelines.

copycmd – Interactive Copy‑Command Reference & Generator

Summary

  • A searchable CLI/TUI (and web) reference that shows flag differences for cp, scp, rsync across Linux, *BSD, macOS, and suggests the most portable command for a given task.
  • Core value: eliminates guesswork and platform‑specific trial‑and‑error when building copy commands.

Details

Key Value
Target Audience Engineers, DevOps, students, and anyone writing shell scripts or ad‑hoc commands
Core Feature Interactive picker: choose source type, options (preserve timestamps, links, reflink), target OS → outputs exact command with explanations
Tech Stack Go (for fast binary), fuzzy finder (fzf) or termui for TUI, static data sourced from manpages, optional web frontend with React
Difficulty Low
Monetization Hobby

Notes

  • Users expressed frustration with “-r and -R mean entirely different things” (5555watch) and “I always have this vague fear that I'll rsync in the wrong direction” (CoastalCoder); a reference tool would directly address those pain points.
  • Could become a go‑to cheat‑sheet shared in dev teams and featured in shell‑plugin ecosystems.

ShellGuard – Portable Command Linter & Validator

Summary

  • A shell plugin (bash/zsh/fish) that lint‑checks commands against the local OS’s manpages or a curated DB, warns about non‑portable flags, and suggests safer alternatives (e.g., using cp -a or rsync).
  • Core value: catches hallucinated or incorrect options from LLMs and manual typos before they run, increasing script reliability.

Details

Key Value
Target Audience Shell power users, automation engineers, and teams that rely on LLMs for command generation
Core Feature Real‑time validation: on command entry, flags are checked; unsupported/misused options trigger inline hints with portable replacements
Tech Stack Rust core (parsing & manpage lookup), shell‑specific integration scripts, optional online DB for cloud‑hosted updates
Difficulty Medium
Monetization Revenue-ready: "Saas tier for enterprise – centralized policy management & audit logs ($12/seat/mo)"

Notes

  • Several commenters worried “LLMs hallucinate these switches incorrectly” (xrd) and wanted a way to “know if LLMs hallucinate these switches” – ShellGuard gives immediate feedback.
  • The tool would generate lively discussion on HN about improving CLI usability and reducing silent failures in automation pipelines.

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