Look at Device::SerialPort, Device::SerialPort::Arduino, or Win32::SerialPort if on windows.

:) serialport isn't usb , are you sure about that?

Yes. Have used Device::SerialPort::Arduino to read data coming from the USB interface on the chipKIT UNO PIC based Arduino clone. The chipKIT UNO uses the FTDI FT232R USB serial converter chip and FTDI FT232R drivers are available on my Unbuntu 10.10 laptop. This is a pretty commonly used USB support chip.

# Perl Polling Test

# Title: Perl to chipKIT Serial Poll Test
# Author: James M. Lynes, Jr.
# Version: 1.0
# Creation Date: June 10, 2012
# Modification Date: June 10, 2012

use strict;
use warnings;

# Initialize the serial port - creates the serial port object $Arduino

use Device::SerialPort::Arduino;

  my $Arduino = Device::SerialPort::Arduino->new(
    port     => '/dev/ttyUSB0',
    baudrate => 9600,
    databits => 8,
    parity   => 'none',
  );

while(1) {
  $Arduino->communicate('P');                     # Send a poll
  print ($Arduino->receive(), "\n");              # Print poll respons
+e
  sleep(1);                                       # Delay until next p
+oll
}
[download]

James

There's never enough time to do it right, but always enough time to do it over...