MCP Shell Server
A secure shell command execution server implementing the Model Context Protocol (MCP). This server allows remote execution of whitelisted shell commands with support for stdin input.
Features
- Secure Command Execution: Only whitelisted commands can be executed
- Standard Input Support: Pass input to commands via stdin
- Comprehensive Output: Returns stdout, stderr, exit status, and execution time
- Shell Operator Safety: Validates commands after shell operators (; , &&, ||, |)
- Timeout Control: Set maximum execution time for commands
MCP client setting in your Claude.app
Published version
code ~/Library/Application\ Support/Claude/claude_desktop_config.json{
"mcpServers": {
"shell": {
"command": "uvx",
"args": [
"mcp-shell-server"
],
"env": {
"ALLOW_COMMANDS": "ls,cat,pwd,grep,wc,touch,find"
}
},
}
}Local version
Configuration
code ~/Library/Application\ Support/Claude/claude_desktop_config.json{
"mcpServers": {
"shell": {
"command": "uv",
"args": [
"--directory",
".",
"run",
"mcp-shell-server"
],
"env": {
"ALLOW_COMMANDS": "ls,cat,pwd,grep,wc,touch,find"
}
},
}
}Installation
pip install mcp-shell-serverUsage
Starting the Server
ALLOW_COMMANDS="ls,cat,echo" uvx mcp-shell-server
# Or using the alias
ALLOWED_COMMANDS="ls,cat,echo" uvx mcp-shell-serverThe ALLOW_COMMANDS (or its alias ALLOWED_COMMANDS ) environment variable specifies which commands are allowed to be executed. Commands can be separated by commas with optional spaces around them.
Valid formats for ALLOW_COMMANDS or ALLOWED_COMMANDS:
ALLOW_COMMANDS="ls,cat,echo" # Basic format
ALLOWED_COMMANDS="ls ,echo, cat" # With spaces (using alias)
ALLOW_COMMANDS="ls, cat , echo" # Multiple spacesRequest Format
# Basic command execution
{
"command": ["ls", "-l", "/tmp"]
}
# Command with stdin input
{
"command": ["cat"],
"stdin": "Hello, World!"
}
# Command with timeout
{
"command": ["long-running-process"],
"timeout": 30 # Maximum execution time in seconds
}
# Command with working directory and timeout
{
"command": ["grep", "-r", "pattern"],
"directory": "/path/to/search",
"timeout": 60
}Response Format
Successful response:
{
"stdout": "command output",
"stderr": "",
"status": 0,
"execution_time": 0.123
}Error response:
{
"error": "Command not allowed: rm",
"status": 1,
"stdout": "",
"stderr": "Command not allowed: rm",
"execution_time": 0
}Security
The server implements several security measures:
- Command Whitelisting: Only explicitly allowed commands can be executed
- Shell Operator Validation: Commands after shell operators (; , &&, ||, |) are also validated against the whitelist
- No Shell Injection: Commands are executed directly without shell interpretation
Development
Setting up Development Environment
- Clone the repository
git clone https://github.com/yourusername/mcp-shell-server.git
cd mcp-shell-server- Install dependencies including test requirements
pip install -e ".[test]"Running Tests
pytestAPI Reference
Request Arguments
| Field | Type | Required | Description |
|---|---|---|---|
| command | string[] | Yes | Command and its arguments as array elements |
| stdin | string | No | Input to be passed to the command |
| directory | string | No | Working directory for command execution |
| timeout | integer | No | Maximum execution time in seconds |
Response Fields
| Field | Type | Description |
|---|---|---|
| stdout | string | Standard output from the command |
| stderr | string | Standard error output from the command |
| status | integer | Exit status code |
| execution_time | float | Time taken to execute (in seconds) |
| error | string | Error message (only present if failed) |
Requirements
- Python 3.11 or higher
- mcp>=1.1.0
License
MIT License - See LICENSE file for details
