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# Shell MCP Server
A Node.js implementation of the Model Context Protocol (MCP) that provides secure shell command execution capabilities. This server allows AI models to execute shell commands in a controlled environment with built-in security measures. Easily integrates with [Claude Desktop](https://claude.ai/download) for connecting Claude with your shell.
<a href="https://glama.ai/mcp/servers/jwkd5nmnh7">
<img width="380" height="200" src="https://glama.ai/mcp/servers/jwkd5nmnh7/badge" alt="Shell Server MCP server" />
</a>
## Features
- MCP-compliant server implementation
- Secure command execution with blacklist protection
- Command existence validation
- Standard I/O based transport
- Error handling and graceful shutdown
## Installation
Run `npx mcp-shell`.
To add it to Claude Desktop, run `npx mcp-shell config`. Or add `npx -y mcp-shell` to your config manually.
Start (or restart) [Claude Desktop](https://claude.ai/download) and you should see the MCP tool listed on the landing page.
## Security Features
The server implements several security measures:
1. Command Blacklisting
- Prevents execution of dangerous system commands
- Blocks access to critical system modifications
- Protects against file system destruction
- Prevents privilege escalation
2. Command Validation
- Verifies command existence before execution
- Validates against the blacklist
- Returns clear error messages for invalid commands
## Available Tools
The server provides one tool:
### run_command
Executes a shell command and returns its output.
**Input Schema:**
```json
{
"type": "object",
"properties": {
"command": { "type": "string" }
}
}
```
**Response:**
- Success: Command output as plain text
- Error: Error message as plain text
## Blacklisted Commands
The following command categories are blocked for security:
- File System Destruction Commands (rm, rmdir, del)
- Disk/Filesystem Commands (format, mkfs, dd)
- Permission/Ownership Commands (chmod, chown)
- Privilege Escalation Commands (sudo, su)
- Code Execution Commands (exec, eval)
- System Communication Commands (write, wall)
- System Control Commands (shutdown, reboot, init)
## Error Handling
The server includes comprehensive error handling:
- Command not found errors
- Blacklisted command errors
- Execution errors
- MCP protocol errors
- Graceful shutdown on SIGINT
## Implementation Details
The server is built using:
- Model Context Protocol SDK
- StdioServerTransport for communication
- execa for command execution
- command-exists for command validation
## Development
To modify the security settings, you can:
1. Edit the `BLACKLISTED_COMMANDS` set to adjust blocked commands
2. Modify the `validateCommand` function to add additional validation rules
3. Enhance the command parsing logic in the `CallToolRequestSchema` handler
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