diff --git a/emori.ino b/emori.ino
index b31bbf5..62e36ff 100644
--- a/emori.ino
+++ b/emori.ino
@@ -1,4 +1,3 @@
-
 // https://code.google.com/p/rc-switch/
 #include <RCSwitch.h>
 
@@ -9,7 +8,6 @@ boolean command_complete = false;
 RCSwitch rc_switch = RCSwitch();
 
 
-
 void setup()  {
   pinMode(led_stripe, OUTPUT);
   Serial.begin(9600);
@@ -18,10 +16,10 @@ void setup()  {
 } 
 
 void process_command(String command, String param) {
-  if (command == "fade") fade_to(param.toInt());
-  if (command == "led") toggle_stripes(param);
-  if (command == "on") switch_230("on", param);
-  if (command == "off") switch_230("off", param);
+  if (command == "fade" || command == "f") fade_to(param.toInt());
+  if (command == "led" || command == "l") toggle_stripes(param);
+  if (command == "on" || command == "1") switch_230("on", param);
+  if (command == "off" || command == "0") switch_230("off", param);
   
   Serial.println("Ok");
 }
@@ -85,4 +83,3 @@ void serialEvent() {
     }
   }
 }
-
diff --git a/emori.rb b/emori.rb
index 6bc7dad..918018b 100755
--- a/emori.rb
+++ b/emori.rb
@@ -3,6 +3,12 @@
 require 'rubygems'
 require 'serialport'
 
+# If the main monitor is off, the Arduino is also off because it is connected to
+# the USB hub inside the monitor. So, if the main monitor is off, the user can't
+# control the lights any more and the LED stripes are off too.
+abort unless File.exists?('/dev/ttyUSB0')
+
+# Create the serial connection and send the given command.
 SerialPort.open('/dev/ttyUSB0', 9600, 8, 1, SerialPort::NONE) do |s|
   s.puts(ARGV.join(' '))
 end