gemini-cli

Shell Tool (run_shell_command)

This document describes the run_shell_command tool for the Gemini CLI.

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. On Windows, the command will be executed with cmd.exe /c. On other platforms, the command will be 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.

How to use run_shell_command with the Gemini CLI

When using run_shell_command, the command is executed as a subprocess. run_shell_command can start background processes using &. 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.")

run_shell_command examples

List files in the current directory:

run_shell_command(command="ls -la")

Run a script in a specific directory:

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

Start a background server:

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

Important notes

• Security: Be cautious when executing commands, especially those constructed from user input, to prevent security vulnerabilities.
• Interactive commands: Avoid commands that require interactive user input, as this can cause the tool to hang. Use non-interactive flags if available (e.g., npm init -y).
• Error handling: Check the Stderr, Error, and Exit Code fields to determine if a command executed successfully.
• Background processes: When a command is run in the background with &, 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.

Environment Variables

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

Command Restrictions

You can restrict the commands that can be executed by the run_shell_command tool by using the coreTools and excludeTools settings in your configuration file.

• coreTools: To restrict run_shell_command to a specific set of commands, add entries to the coreTools list in the format run_shell_command(<command>). For example, "coreTools": ["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.
• excludeTools: To block specific commands, add entries to the excludeTools list in the format run_shell_command(<command>). For example, "excludeTools": ["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 excludeTools 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 coreTools.

Command Restriction Examples

Allow only specific command prefixes

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

{
  "coreTools": ["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:

{
  "coreTools": ["run_shell_command"],
  "excludeTools": ["run_shell_command(rm)"]
}

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

Blocklist takes precedence

If a command prefix is in both coreTools and excludeTools, it will be blocked.

{
  "coreTools": ["run_shell_command(git)"],
  "excludeTools": ["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 excludeTools:

{
  "excludeTools": ["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.

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