# Bun File Io

Use this when you are working on file operations like reading, writing, scanning, or...

- Repository: https://github.com/synthetic-sciences/openscience (4321 stars)
- Category: Writing
- License: Apache-2.0
- Last updated: 2026-10-30
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add synthetic-sciences/openscience --skill bun-file-io -g -a claude-code -y`
Codex: `npx skills add synthetic-sciences/openscience --skill bun-file-io -g -a codex -y`
Cursor: `npx skills add synthetic-sciences/openscience --skill bun-file-io -g -a cursor -y`
Gemini CLI: `npx skills add synthetic-sciences/openscience --skill bun-file-io -g -a gemini-cli -y`

## Description

Use this when you are working on file operations like reading, writing, scanning, or deleting files. It summarizes the preferred file APIs and patterns used in this repo. It also notes when to use filesystem helpers for directories.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

## Use this when

- Editing file I/O or scans in `backend/cli` (the OpenScience CLI package)
- Handling directory operations or external tools

## Bun file APIs (from Bun docs)

- `Bun.file(path)` is lazy; call `text`, `json`, `stream`, `arrayBuffer`, `bytes`, `exists` to read.
- Metadata: `file.size`, `file.type`, `file.name`.
- `Bun.write(dest, input)` writes strings, buffers, Blobs, Responses, or files.
- `Bun.file(...).delete()` deletes a file.
- `file.writer()` returns a FileSink for incremental writes.
- `Bun.Glob` + `Array.fromAsync(glob.scan({ cwd, absolute, onlyFiles, dot }))` for scans.
- Use `Bun.which` to find a binary, then `Bun.spawn` to run it.
- `Bun.readableStreamToText/Bytes/JSON` for stream output.

## When to use node:fs

- Use `node:fs/promises` for directories (`mkdir`, `readdir`, recursive operations).

## Repo patterns

- Prefer Bun APIs over Node `fs` for file access.
- Check `Bun.file(...).exists()` before reading.
- For binary/large files use `arrayBuffer()` and MIME checks via `file.type`.
- Use `Bun.Glob` + `Array.fromAsync` for scans.
- Decode tool stderr with `Bun.readableStreamToText`.
- For large writes, use `Bun.write(Bun.file(path), text)`.

## Quick checklist

- Use Bun APIs first.
- Use `path.join`/`path.resolve` for paths.
- Prefer promise `.catch(...)` over `try/catch` when possible.