home-assistant.io/source/_docs/tools/check_config.markdown

title	description
check_config	Script to perform a check of the current configuration

Test any changes to your configuration.yaml file before launching Home Assistant. This script allows you to test changes without the need to restart Home Assistant.

hass --script check_config

The script has further options like checking configuration files which are not located in the default directory or showing your secrets for debugging.

$ hass --script check_config -h
usage: hass [-h] [--script {check_config}] [-c CONFIG] [-i [INFO]] [-f] [-s]

Check Home Assistant configuration.

optional arguments:
  -h, --help            show this help message and exit
  --script {check_config}
  -c CONFIG, --config CONFIG
                        Directory that contains the Home Assistant
                        configuration
  -i [INFO], --info [INFO]
                        Show a portion of the config
  -f, --files           Show used configuration files
  -s, --secrets         Show secret information