Use expect to connect to a serial port (e.g., for Arduino)

usb0

#!/usr/bin/expect -f

# device
set modem /dev/ttyUSB0

# keep it open
exec sh -c "sleep 3 < $modem" &

# serial port parameters
exec stty -F $modem 9600 raw -clocal -echo -istrip -hup

# connect
send_user "connecting to $modem, exit with ~.\n"
spawn -open [open $modem w+]
interact {
    ~. exit
    ~~ {send "\034"}
}