This allows you to override the config file to use, instead of the default (usually smb.conf). There is a chicken and egg problem here as this option is set in the config file! For this reason, if the name of the config file has changed when the parameters are loaded then it will reload them from the new config file. This option takes the usual substitutions, which can be very useful. If the config file doesn't exist then it won't be loaded (allowing you to special case the config files of just a few clients). Example: config file = /usr/local/samba/lib/smb.conf.%m