shell_cat
Display file contents by concatenating them for viewing or processing within the Shell-MCP server's secure execution environment.
Instructions
Concatenate and display file contents
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| args | No | Command arguments |
Implementation Reference
- src/index.ts:45-85 (handler)Main MCP tool call handler that specifically maps tool name 'shell_cat' (by replacing 'shell_' with '') to internal 'shell.cat' config, validates args, executes via CommandExecutor, collects stdout, and returns text content.server.setRequestHandler(CallToolRequestSchema, async (request) => { try { const command = String(request.params?.name || ''); const fullCommand = `shell.${command.replace('shell_', '')}`; // Replace shell_ back to shell. if (!(fullCommand in allowedCommands)) { return { content: [{ type: "text", text: `Unknown command: ${command}` }], isError: true }; } const actualCommand = allowedCommands[fullCommand].command; const args = Array.isArray(request.params?.arguments?.args) ? request.params.arguments.args.map(String) : []; validator.validateCommand(actualCommand, args); const stream = await executor.execute(actualCommand, args); return { content: [{ type: "text", text: await new Promise((resolve, reject) => { const chunks: Buffer[] = []; stream.stdout.on('data', (chunk: Buffer) => chunks.push(chunk)); stream.stdout.on('end', () => resolve(Buffer.concat(chunks).toString())); stream.stdout.on('error', reject); }) }] }; } catch (error) { return { content: [{ type: "text", text: `Command execution failed: ${error instanceof Error ? error.message : String(error)}` }], isError: true }; } });
- src/index.ts:27-43 (registration)Registers the 'shell_cat' tool (by converting 'shell.cat' key to 'shell_cat') with its description and generic input schema for string array args.server.setRequestHandler(ListToolsRequestSchema, async () => { const tools = Object.entries(allowedCommands).map(([name, config]) => ({ name: name.replace('shell.', 'shell_'), // Replace shell. with shell_ description: config.description, inputSchema: { type: "object", properties: { args: { type: "array", items: { type: "string" }, description: "Command arguments" } } } })); return { tools }; });
- src/config/allowlist.ts:21-26 (registration)Allowlist configuration entry for 'shell.cat' command, defining the executable 'cat', description, allowed arguments, and timeout used for the 'shell_cat' tool.'shell.cat': { command: 'cat', description: 'Concatenate and display file contents', allowedArgs: ['-n', '-b', '--help', '*'], timeout: 3000 },
- src/core/executor.ts:31-121 (handler)Core execution logic that spawns the child process for the base command ('cat' for shell.cat/shell_cat) with provided arguments, handling streams, timeouts, and errors.async execute( command: string, args: string[] = [], options: ExecuteOptions = {} ): Promise<{ stdout: Readable }> { const commandKey = `${command} ${args.join(' ')}`; try { // Check security await this.securityChecker.validateCommand(command, args, options); // Check cache const cached = this.cache.get(commandKey); if (cached) { this.logger.debug('Using cached command result', { command, args }); return this.createStreamFromCache(cached); } // Remove 'shell.' prefix for execution const baseCommand = command.replace('shell.', ''); // Execute command this.logger.debug('Starting command execution', { command, args, options }); const childProcess = spawn(baseCommand, args, { stdio: ['ignore', 'pipe', 'pipe'], timeout: options.timeout, cwd: options.cwd, env: { ...process.env, ...options.env }, signal: options.signal }); this.currentProcess = childProcess; // Error handling childProcess.on('error', (error: Error) => { this.logger.error('Command execution error', { command, args, error: error.message }); throw new ToolError( 'PROCESS_ERROR', 'Command execution error', { command, args, error: error.message } ); }); // Timeout handling if (options.timeout) { setTimeout(() => { if (childProcess.exitCode === null) { this.logger.warn('Command execution timeout', { command, args, timeout: options.timeout }); childProcess.kill(); throw new ToolError( 'TIMEOUT', 'Command execution timeout', { command, args, timeout: options.timeout } ); } }, options.timeout); } if (!childProcess.stdout) { throw new ToolError( 'STREAM_ERROR', 'Unable to get command output stream', { command, args } ); } // Monitor process status childProcess.on('exit', (code, signal) => { this.logger.debug('Command execution completed', { command, args, exitCode: code, signal }); }); return { stdout: childProcess.stdout };