Arduino to upload a hex file to another device?

Forum 2005-2010 (read only) General Frequently-Asked Questions
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you will need to upload the arduinoisp sketch onto a arduino (dont know if the mega 8 will work for this) then you can use avr dude as if it was connected to an avrisp programmer

http://www.ladyada.net/learn/avr/avrdude.html