AVRDude programming

What language does one use to modify avrdude.conf?

What is its exact function? How does boards.txt fit in with this function?

I can guess that boards has the definitions for the board I use, but wouldn’t avrdude take care of this?

AVRdude can recognize microcontroller and fuses but not code setup (clock, cores), that info is specified in the boards.txt, and also the fuses configuration.

What do you want to do or what are you needs with avr dude?

I'm using the iMac. I can upload a sketch to my Duemilanove with the original avrdude. There is a version that I want to use that I got from instructables that works on my PC. I want it to work on the iMac. However, when I substitute it I get this:

Binary sketch size: 5,438 bytes (of a 30,720 byte maximum)
avrdude: parallel port access not available in this configuration
avrdude: error at /Users/Documents/Arduino/Arduino101.app/Contents/Resources/Java/hardware/tools/avr/etc/avrdude.conf:727: programmer type not specified

What should I look for to fix this?

any takers?