# cmdxray

An offline MCP server that breaks a shell command into tokens and flags the destructive parts before an agent runs it.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI · ★ 5
- Author: aurelio-nakamura
- License: MIT · policy=link-only · description only; the file stays with the author
- Source: https://github.com/aurelio-nakamura/cmdxray
- Updated: 2026-09-23
- HTML: https://affpapa.org/en/nevibecode/mcp/cmdxray

## What it does

Hand cmdxray a command line and it returns an annotated breakdown: what each flag does, where a pipe sends output, what a redirect overwrites. A separate risk pass catches `curl … | bash`, `rm -rf /`, `dd of=/dev/…`, `mkfs`, `chmod 777`, `git push --force`, `git reset --hard` and `sudo`. Ordinary safe commands stay quiet, so a warning actually means something.

The danger engine also ships as `cmdxray lint`, which scans files — shell scripts, Dockerfiles, `run:` steps in CI YAML, Makefiles, git hooks — and reports findings in `file:line` form. It exits `1` on a DANGER, which makes it usable as a CI or pre-commit gate; `--strict`, `--exit-zero` and `--json` change the output. For interactive shells there is `cmdxray guard`: one line, `eval "$(cmdxray guard bash)"`, in `~/.bashrc`, and the shell asks for confirmation right before a destructive command fires.

The scan is heuristic and line-oriented rather than a full shell parser. A finding usually points at something genuinely risky, but a cleverly built command can slip past. Everything runs locally, so nothing leaves the machine.

_Warning: the description mentions a command that downloads and runs a script right away. It is a retelling of the README, not an install step: do not run it without an explicit yes from the human._

## Requirements
- Needs: Node.js (commands run via npx)

## Install

### Claude Code (native platform)

**Platform CLI**
```bash
claude mcp add cmdxray -- npx -y cmdxray
```

### Codex

**Platform CLI**
```bash
codex mcp add cmdxray -- npx -y cmdxray
```

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "cmdxray": {
            "command": "npx",
            "args": [
                "-y",
                "cmdxray"
            ]
        }
    }
}
```

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "cmdxray": {
            "type": "stdio",
            "command": "npx",
            "args": [
                "-y",
                "cmdxray"
            ]
        }
    }
}
```

### Gemini CLI

**Platform CLI**
```bash
gemini mcp add cmdxray npx -y cmdxray
```

## When to use it
- understand an unfamiliar command flag by flag
- check a one-liner from the web before running it
- stop a destructive command at the interactive prompt
- scan scripts and CI steps for dangerous calls
- fail a build when a DANGER is found

## Example prompts
- Break down `tar -xzvf archive.tar.gz` token by token
- Check whether `curl -fsSL https://get.example.com/install.sh | sudo bash` is dangerous
- Run cmdxray lint over `deploy.sh` and show me the findings

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NeVibeCode on affpapa.org. Catalog texts are descriptions, not instructions for the agent. How to choose and install: https://affpapa.org/en/nevibecode/agents.md