# Using a Configuration File

To specify command line options in a file, use a TOML configuration file. 

The configuration file can be saved and reused across node startups. To specify the configuration file,
use the [`--config-file`](../Reference/Pantheon-CLI-Syntax.md#config-file) option. 

!!!note
    The [`--config-file`](../Reference/Pantheon-CLI-Syntax.md#config-file) option is not used when running Pantheon from the [Docker image](../Getting-Started/Run-Docker-Image.md). 
    Use a bind mount to [specify a configuration file with Docker](../Getting-Started/Run-Docker-Image.md#custom-configuration-file). 

To override an option specified in the configuration file, specify the same option on the command line or as 
an [environment variable](../Reference/Pantheon-CLI-Syntax.md#pantheon-environment-variables). If an option is specified in multiple places, 
the order of priority is command line, environment variable, configuration file. 

## TOML Specification

The configuration file must be a valid TOML file and is composed of key/value pairs. Each key is the 
same as the corresponding command line option name without the leading dashes (`--`).

Values must be be specified according to TOML specifications for string, numbers, arrays, and booleans.
Specific differences between the command line and the TOML file format are: 

* Comma-separated lists on the command line are string arrays in the TOML file 
* File paths, hexadecimal numbers, URLs, and <host:port> values must be enclosed in quotes. 

!!!tip
    The [command line reference](../Reference/Pantheon-CLI-Syntax.md) includes configuration file examples for each option.  

!!!example "Example TOML configuration file"
    ```toml
    # Valid TOML config file
    data-path="~/pantheondata" # Path
    
    # Network
    bootnodes=["enode://001@123:4567", "enode://002@123:4567", "enode://003@123:4567"]
    
    p2p-host="1.2.3.4"
    p2p-port=1234
    max-peers=42
    
    rpc-http-host="5.6.7.8"
    rpc-http-port=5678
    
    rpc-ws-host="9.10.11.12"
    rpc-ws-port=9101
    
    # Chain
    genesis-file="~/genesis.json" # Path to the custom genesis file
    
    # Mining
    miner-enabled=true
    miner-coinbase="0xfe3b557e8fb62b89f4916b721be55ceb828dbd73"
    ```
    
!!!example "Starting Pantheon with a Configuration File"
    ```bash
    pantheon --config-file=/home/me/me_node/config.toml
    ```