$ lsof /dev/ttyUSB0
COMMAND  PID     USER   FD   TYPE DEVICE SIZE/OFF      NODE NAME
avrdude 7356   jippie    3u   CHR  188,0      0t0 266450197 /dev/ttyUSB0

€ fuser /dev/ttyUSB0
/dev/ttyUSB0:         7356

$ ps -fp 7356
UID      PID  PPID  C STIME TTY          TIME CMD
jippie  7698 28116  1 20:34 pts/8    00:00:00 avrdude -patmega1280 -carduino -P/dev/ttyUSB002 -b57600 -D -Uflash:r:/tmp/flash:i

$ ps -ef | grep 7356
jippie  7698 28116  1 20:34 pts/8    00:00:00 avrdude -patmega1280 -carduino -P/dev/ttyUSB002 -b57600 -D -Uflash:r:/tmp/flash:i