koocotte:
[quote author=The Clever Monkey link=topic=108621.msg820765#msg820765 date=1339251848]
Read the man page on udev and udevd. You can add custom instructions to this daemon to make this work out of the box.
This my previous message as help and bugreport.
I just write the previous message with a simple solution for people that will be in trouble. The IDE does not report any error for being denied access to /dev/ttyACM0; and I did not found any instruction to resolv this problem on the arduino website.
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I not saying what you did is wrong; I'm saying there is a recommended solution in modern Linux.
By using udev you can put in rules for any device id you ever use. And note that /dev/ttyACM0 doesn't actually appear on my Debian based box. With udev it sets the mode, the ownership and gives it an easy to remember softlink.
Also, this is not strictly a problem with Arduino. It is a problem for anyone needing to use any bus-based PTTY. So this is why the answer is found in these forums. I'm pretty sure if you looked at the full error message (see preferences) from avrdude in Arduino, and search on that error message here, you'll see lots of refs to udev, and how to configure it.