fauxnix

Run Linux-style commands on Windows — natively, deterministically, no VM, no WSL.

fauxnix is a bash→PowerShell translation layer built for AI agents. Your agent keeps writing the bash it already knows (ls -la | grep foo, find . -name '*.ts' | wc -l, kill -9 1234), and fauxnix deterministically translates each command into PowerShell, executes it natively, and hands back output that looks like GNU/Linux: ls -l columns, bash-style error messages, coreutils exit codes, UTF-8/GBK handled automatically.

One-command install for Claude Code · Codex · OpenCode · Kimi Code · Qwen Code, plus any MCP client. 109 translated commands · 1,044 automated tests · 270-case Git Bash differential corpus plus 41 supplementary checks · zero LLM calls at runtime.

This checkout prepares v2.0.0. See migration and release notes for the Node.js requirement, changed file-operation contracts and verification limits. The npm badge and @latest examples show the published version until publication completes.

Try it now — no install

npx fauxnix-cli@latest "ls -la src | head -3"
npx fauxnix-cli@latest translate "find . -name '*.log' -mtime +7 -delete"

$ fauxnix "ls -la src | head -2"
-rw-r--r-- 1 me me 1204 Aug 16 09:12 ast.ts
-rw-r--r-- 1 me me 8192 Aug 16 09:12 cli.ts

$ fauxnix "cat nope.txt"
cat: nope.txt: No such file or directory        # not a PowerShell stack trace

Connect your agent — one command

npm install -g fauxnix-cli
fauxnix install --claude     # or --codex / --opencode / --kimi / --qwen
fauxnix doctor               # verifies encoding, harness config, and MCP round-trip

Idempotent; prints exactly what changed. Manual configurations below if you prefer to edit config files yourself.

npm package name is fauxnix-cli (the fauxnix name on npm belongs to an unrelated 2015 websocket library); the installed command is fauxnix. Requires Windows with PowerShell 5.1+ (built-in) and Node.js ≥ 22.20.0. Node 18/20 are unsupported in v2. Current Node 22/24 LTS patches are tested. Published v1.0.0 retains its original metadata.

Manual config per harness

Claude Code

claude mcp add fauxnix -- fauxnix mcp

Codex (~/.codex/config.toml or codex mcp add fauxnix -- fauxnix mcp)

[mcp_servers.fauxnix]
command = "fauxnix"
args = ["mcp"]

Note: in non-interactive codex exec mode, MCP tool calls are auto-denied by the approval layer; pass --dangerously-bypass-approvals-and-sandbox (or run interactively and approve once).

OpenCode (opencode.json)

{
  "mcp": {
    "fauxnix": { "type": "local", "command": ["fauxnix", "mcp"] }
  }
}

Kimi Code — MCP servers live in a JSON file, not the TOML config: ~/.kimi-code/mcp.json

{
  "mcpServers": {
    "fauxnix": { "command": "fauxnix", "args": ["mcp"] }
  }
}

Qwen Code (~/.qwen/settings.json)

fauxnix install --qwen

The installer preserves the rest of settings.json and writes an absolute Node + package-entry launcher so Qwen startup does not depend on its working directory or PATH order. See the Qwen example for the generated JSON shape.

Any MCP client — stdio server: fauxnix mcp. The tool name is bash (override with FAUXNIX_TOOL_NAME). The tool description already teaches the model the supported subset, so no system-prompt changes are required.