The config system is used for user-configurable options. They are backed by environment variables and config files.

Here are the layers of config, with each layer overriding the layer below it:

Use the config_dir and config_env_var_prefix options in the constructor of CLI to set the config directory and environment variable prefix.

Here's an example:

Let's assume config_dir=~/.myconfig and config_env_var_prefix='CLI'.

Environment variable format export PREFIX_SECTION_OPTION=value.

Config file format:

[section]
option = value

So to set the output type of commands, a user can set the environment variable CLI_CORE_OUTPUT or specify the section and option in the config file. The environment variable will override the config file. Lastly, some configurations (like output type) can be specified on a command-by-command basis also.