Made ShellCommands example more physical

hardware/arduino/avr/libraries/Bridge/examples/ShellCommands/ShellCommands.ino

@@ -3,18 +3,21 @@
  Running shell coommands using Process class. 
  
  This sketch demonstrate how to run linux shell commands
- using an Arduino Yún. 
-
+ using an Arduino Yún. It runs the wifiCheck script on the linino side
+ of the Yun, then uses grep to get just the signal strength line.
+ Then it uses parseInt() to read the wifi signal strength as an integer,
+ and finally uses that number to fade an LED using analogWrite().
+ 
  The circuit:
- * Arduino Yun
+ * Arduino Yun with LED connected to pin 9
  
  created 12 Jun 2013
  by Cristian Maglie
- modified 21 June 2013
+ modified 25 June 2013
  by Tom Igoe
  
  This example code is in the public domain.
-
+ 
  */
 
 #include <Process.h>
@@ -27,15 +30,23 @@ void setup() {
 
 void loop() {
   Process p;
-  // This command line prints the name of the wireless network
-  // that the board is connected to, or the network which the board has created:
-  p.runShellCommand(F("lua /usr/lib/lua/pretty_wifi_info.lua | grep SSID"));
+  // This command line runs the wifiCheck script, (lua /arduino/pretty...), then 
+  // sends the result to the grep command to look for a line containing the word
+  // "Signal:"  the result is passed to this sketch:
+  p.runShellCommand("lua /arduino/pretty_wifi_info.lua | grep Signal");
 
-  // Read command output
+  // do nothing until the process finishes, so you get the whole output:
+  while(p.running());  
+
+  // Read command output. runShellCommand() should have passed "Signal: xx&":
   while (p.available()) {
-    char c = p.read();
-    Serial.print(c);
+    int result = p.parseInt();                // look for an integer
+    int signal = map(result, 0, 100, 0, 255); // map result from 0-100 range to 0-255
+    analogWrite(9, signal);                   // set the brightness of LED on pin 9
+    Serial.println(result);                   // print the number as well
   } 
-  while (true);    // do nothing more
+  delay(5000);    // wait 5 seconds before you do it again
 }
 
+
+