upload does not reset arduino in ubuntu

so I finally got this working on linux and now I have an interesting observation.

When I load blink after plugging in the arduino it works fine.

however when I modify the code in any way and re-upload the arduino does not actually reset the arduino. i have to either hit the reset button or unplug and plug in the arduino.

is there something I'm doing wrong? I never had to do this with the PC version

If you hit the reset button when uploading does it successful finishes the upload ?

no it says it's not responding. I have to hit reset after it uploads.