# Custom Filters

Bashly supports custom filter functions for your commands. These filters allow you to define custom conditions that can prevent your command from running unless they are met.

This is how it works:

1. In your bashly configuration file, commands may have a filters option, specifying an array of one or more function names.
2. Whenever your run your script, it will look for functions with that name, prefixed by filter_ and will run them before calling the command code.
3. If any of the functions returns any string, it is considered an error. The string will be displayed on screen, as the error message.

name: viewer
filters:
- docker_running

filter_docker_running() {
  docker info > /dev/null 2>&1 || echo "Docker must be running"
}

Filters Example