File name of configuration file to read from. Defaults to the value of
the 'R_CONFIGFILE_ACTIVE' environment variable ('config.cfg' if the
variable does not exist and JSON/INI/YAML/TOML format only)
out.file
Output path of configuration file. Defaults to the value of
the 'R_CONFIGFILE_ACTIVE' environment variable ('config.cfg' if the
variable does not exist)