set_config_file (3) - Linux Man Pages
set_config_file: Sets the configuration file. Allegro game programming library.
NAMEset_config_file - Sets the configuration file. Allegro game programming library.
DESCRIPTIONSets the configuration file to be used by all subsequent config functions. If you don't call this function, Allegro will use the default `allegro.cfg' file, looking first in the same directory as your program and then in the directory pointed to by the ALLEGRO environment variable and the usual platform-specific paths for configuration files. For example it will look for `/etc/allegro.cfg' under Unix.
All pointers returned by previous calls to get_config_string() and other related functions are invalidated when you call this function! You can call this function before install_allegro() to change the configuration file, but after set_uformat() if you want to use a text encoding format other than the default.