try {
    // Enter the device file for your USB printer here
    // You can check the tutorial here: https://mike42.me/blog/2015-03-getting-a-usb-receipt-printer-working-on-linux
    $connector = new FilePrintConnector("/dev/usb/lp0");
    /* Print a "Hello world" receipt" */
    $printer = new Printer($connector);
    $printer -> text("Hello World!\n");
    $printer -> cut();
    /* Close printer */
    $printer -> close();
} catch (Exception $e) {
    echo "Couldn't print to this printer: " . $e -> getMessage() . "\n";
}

$this->load->library("EscPos.php");

try {
		// Enter the device file for your USB printer here
	  $connector = new Escpos\PrintConnectors\FilePrintConnector("/dev/usb/lp0");
		   
		/* Print a "Hello world" receipt" */
		$printer = new Escpos\Printer($connector);
		$printer -> text("Hello World!\n");
		$printer -> cut();

		/* Close printer */
		$printer -> close();
} catch (Exception $e) {
	echo "Couldn't print to this printer: " . $e -> getMessage() . "\n";
}