reset via serial

I have a need to remotely reflash firmware via avrdude and I can't find how to reset the arduino over the serial connection. I looked through the IDE code and googled for about 5hrs straight now and can't for the life of me find anything other than someone in the old arduino forum saying the DTR of the serial connection is set low, but i couldn't find any corroboration in the source code or google. any help would be apreciated.

maybe you could do it with a little hardware.. connect a transistor to the reset pin, and connect the base to e.g. pin 13. Set the pin to HIGH when the arduino receives "reset" through the serial port..

i don't know how to do it with pure code, but this might be the easiest way to do it..

The IDE does it via hardware as well that's why the older model arduinos don't support just hitting the upload button. There is lots of documentation for retrofitting the "auto-reset" functionality on older model arduinos but I didn't see anything about the signal the IDE sends to tell it to reset :/ The problem i have is that the firmware seems to become corrupted after a while so it's pretty important that it can be done from the host machine. I might just replace the chip and hope it was a lemon but if I can do it from the host machine I won't have to replace it just yet and I can get it working now instead of when I'm able to get to it next. Edit: so far as i can tell the board was borked. when i got back to it i manually reset it and flashed it but it still wan't working so i swapped the chip for a known working one and it still didn't work :/ Lucky I had an Uno on hand ... now I need to fix my code on the host machine so it updates IRC and twitter correctly XD