IFCONFIG

Checks that a config setting satisfies the given rule; if not, the parent of this node and all its children will be ignored.

Rules beginning with ! will succed if the key is not set in config. All other rules only succeed if the key is set. keys may be defined in the conf file, environment variables, config table if defined. the key 'os' is defined at compile-time to be 'WIN32' or 'UNIX' as apropriate. the key '_config_file' holds the pathname to the config file.