Shell Tool (run_shell_command)

This document describes the run_shell_command tool for Qwen Code.

Description

Use run_shell_command to interact with the underlying system, run scripts, or perform command-line operations. run_shell_command executes a given shell command, including interactive commands that require user input (e.g., vim, git rebase -i) if the tools.shell.enableInteractiveShell setting is set to true.

On Windows, commands are executed with cmd.exe /c. On other platforms, they are executed with bash -c.

Arguments

run_shell_command takes the following arguments:

• command (string, required): The exact shell command to execute.
• description (string, optional): A brief description of the command’s purpose, which will be shown to the user.
• directory (string, optional): The directory (relative to the project root) in which to execute the command. If not provided, the command runs in the project root.
• is_background (boolean, required): Whether to run the command in background. This parameter is required to ensure explicit decision-making about command execution mode. Set to true for long-running processes like development servers, watchers, or daemons that should continue running without blocking further commands. Set to false for one-time commands that should complete before proceeding.

How to use run_shell_command with Qwen Code

When using run_shell_command, the command is executed as a subprocess. You can control whether commands run in background or foreground using the is_background parameter, or by explicitly adding & to commands. The tool returns detailed information about the execution, including:

Required Background Parameter

The is_background parameter is required for all command executions. This design ensures that the LLM (and users) must explicitly decide whether each command should run in the background or foreground, promoting intentional and predictable command execution behavior. By making this parameter mandatory, we avoid unintended fallback to foreground execution, which could block subsequent operations when dealing with long-running processes.

Background vs Foreground Execution

The tool intelligently handles background and foreground execution based on your explicit choice:

Use background execution (is_background: true) for:

• Long-running development servers: npm run start, npm run dev, yarn dev
• Build watchers: npm run watch, webpack --watch
• Database servers: mongod, mysql, redis-server
• Web servers: python -m http.server, php -S localhost:8000
• Any command expected to run indefinitely until manually stopped

Use foreground execution (is_background: false) for:

• One-time commands: ls, cat, grep
• Build commands: npm run build, make
• Installation commands: npm install, pip install
• Git operations: git commit, git push
• Test runs: npm test, pytest

Execution Information

The tool returns detailed information about the execution, including:

• Command: The command that was executed.
• Directory: The directory where the command was run.
• Stdout: Output from the standard output stream.
• Stderr: Output from the standard error stream.
• Error: Any error message reported by the subprocess.
• Exit Code: The exit code of the command.
• Signal: The signal number if the command was terminated by a signal.
• Background PIDs: A list of PIDs for any background processes started.

Usage:

run_shell_command(command="Your commands.", description="Your description of the command.", directory="Your execution directory.", is_background=false)

Note: The is_background parameter is required and must be explicitly specified for every command execution.

run_shell_command examples

List files in the current directory:

run_shell_command(command="ls -la", is_background=false)

Run a script in a specific directory:

run_shell_command(command="./my_script.sh", directory="scripts", description="Run my custom script", is_background=false)

Start a background development server (recommended approach):

run_shell_command(command="npm run dev", description="Start development server in background", is_background=true)

Start a background server (alternative with explicit &):

run_shell_command(command="npm run dev &", description="Start development server in background", is_background=false)

Run a build command in foreground:

run_shell_command(command="npm run build", description="Build the project", is_background=false)

Start multiple background services:

run_shell_command(command="docker-compose up", description="Start all services", is_background=true)

Configuration

You can configure the behavior of the run_shell_command tool by modifying your settings.json file or by using the /settings command in the Qwen Code.

Enabling Interactive Commands

To enable interactive commands, you need to set the tools.shell.enableInteractiveShell setting to true. This will use node-pty for shell command execution, which allows for interactive sessions. If node-pty is not available, it will fall back to the child_process implementation, which does not support interactive commands.

Example settings.json:

{
  "tools": {
    "shell": {
      "enableInteractiveShell": true
    }
  }
}

Showing Color in Output

To show color in the shell output, you need to set the tools.shell.showColor setting to true. Note: This setting only applies when tools.shell.enableInteractiveShell is enabled.

Example settings.json:

{
  "tools": {
    "shell": {
      "showColor": true
    }
  }
}

Setting the Pager

You can set a custom pager for the shell output by setting the tools.shell.pager setting. The default pager is cat. Note: This setting only applies when tools.shell.enableInteractiveShell is enabled.

Example settings.json:

{
  "tools": {
    "shell": {
      "pager": "less"
    }
  }
}

Interactive Commands

The run_shell_command tool now supports interactive commands by integrating a pseudo-terminal (pty). This allows you to run commands that require real-time user input, such as text editors (vim, nano), terminal-based UIs (htop), and interactive version control operations (git rebase -i).

When an interactive command is running, you can send input to it from the Qwen Code. To focus on the interactive shell, press ctrl+f. The terminal output, including complex TUIs, will be rendered correctly.

Important notes

• Security: Be cautious when executing commands, especially those constructed from user input, to prevent security vulnerabilities.
• Error handling: Check the Stderr, Error, and Exit Code fields to determine if a command executed successfully.
• Background processes: When is_background=true or when a command contains &, the tool will return immediately and the process will continue to run in the background. The Background PIDs field will contain the process ID of the background process.
• Background execution choices: The is_background parameter is required and provides explicit control over execution mode. You can also add & to the command for manual background execution, but the is_background parameter must still be specified. The parameter provides clearer intent and automatically handles the background execution setup.
• Command descriptions: When using is_background=true, the command description will include a [background] indicator to clearly show the execution mode.

Environment Variables

When run_shell_command executes a command, it sets the QWEN_CODE=1 environment variable in the subprocess’s environment. This allows scripts or tools to detect if they are being run from within the CLI.

Command Restrictions

You can restrict the commands that can be executed by the run_shell_command tool by using the tools.core and tools.exclude settings in your configuration file.

• tools.core: To restrict run_shell_command to a specific set of commands, add entries to the core list under the tools category in the format run_shell_command(<command>). For example, "tools": {"core": ["run_shell_command(git)"]} will only allow git commands. Including the generic run_shell_command acts as a wildcard, allowing any command not explicitly blocked.
• tools.exclude: To block specific commands, add entries to the exclude list under the tools category in the format run_shell_command(<command>). For example, "tools": {"exclude": ["run_shell_command(rm)"]} will block rm commands.

The validation logic is designed to be secure and flexible:

1. Command Chaining Disabled: The tool automatically splits commands chained with &&, ||, or ; and validates each part separately. If any part of the chain is disallowed, the entire command is blocked.
2. Prefix Matching: The tool uses prefix matching. For example, if you allow git, you can run git status or git log.
3. Blocklist Precedence: The tools.exclude list is always checked first. If a command matches a blocked prefix, it will be denied, even if it also matches an allowed prefix in tools.core.

Command Restriction Examples

Allow only specific command prefixes

To allow only git and npm commands, and block all others:

{
  "tools": {
    "core": ["run_shell_command(git)", "run_shell_command(npm)"]
  }
}

• git status: Allowed
• npm install: Allowed
• ls -l: Blocked

Block specific command prefixes

To block rm and allow all other commands:

{
  "tools": {
    "core": ["run_shell_command"],
    "exclude": ["run_shell_command(rm)"]
  }
}

• rm -rf /: Blocked
• git status: Allowed
• npm install: Allowed

Blocklist takes precedence

If a command prefix is in both tools.core and tools.exclude, it will be blocked.

{
  "tools": {
    "core": ["run_shell_command(git)"],
    "exclude": ["run_shell_command(git push)"]
  }
}

• git push origin main: Blocked
• git status: Allowed

Block all shell commands

To block all shell commands, add the run_shell_command wildcard to tools.exclude:

{
  "tools": {
    "exclude": ["run_shell_command"]
  }
}

• ls -l: Blocked
• any other command: Blocked

Security Note for excludeTools

Command-specific restrictions in excludeTools for run_shell_command are based on simple string matching and can be easily bypassed. This feature is not a security mechanism and should not be relied upon to safely execute untrusted code. It is recommended to use coreTools to explicitly select commands that can be executed.