# 4 Configuration File

AVRDUDE reads a configuration file upon startup which describes all of the parts and programmers that it knows about. The advantage of this is that if you have a chip that is not currently supported by AVRDUDE, you can add it to the configuration file without waiting for a new release of AVRDUDE. Likewise, if you have a parallel port programmer that is not supported by AVRDUDE, chances are good that you can copy and existing programmer definition, and with only a few changes, make your programmer work with AVRDUDE.

AVRDUDE first looks for a system wide configuration file in a platform dependent location. On Unix, this is usually `/usr/local/etc/avrdude.conf`, while on Windows it is usually in the same location as the executable file. The name of this file can be changed using the ‘`-C`’ command line option. After the system wide configuration file is parsed, AVRDUDE looks for a per-user configuration file to augment or override the system wide defaults. On Unix, the per-user file is `.avrduderc` within the user’s home directory. On Windows, this file is the `avrdude.rc` file located in the same directory as the executable.