title: Gatttool in non interactive mode
body: <p>im trying to use gatttool to connect and set value on a Bluetooth le device.
  I need this on non-interactive mode, but can only get the interactive mode working:</p>
  
  <pre><code>pi@raspberrypi:~/x$ sudo gatttool -I
  [                 ][LE]&gt; connect XX:XX:XX:XX:XX:XX
  Attempting to connect to XX:XX:XX:XX:XX:XX
  Connection successful
  [XX:XX:XX:XX:XX:XX][LE]&gt; char-write-req 0x0047 00000000
  Characteristic value was written successfully
  [XX:XX:XX:XX:XX:XX][LE]&gt; char-write-req 0x003f 2424242a008080
  Characteristic value was written successfully
  [XX:XX:XX:XX:XX:XX][LE]&gt; exit
  </code></pre>
  
  <p>But i need something like this:</p>
  
  <pre><code>pi@raspberrypi:~/x$ sudo gatttool -i hci0 -b XX:XX:XX:XX:XX --char-write-req --handle=0x0047 --value=00000000
  Characteristic value was written successfully
  pi@raspberrypi:~/x$ sudo gatttool -i hci0 -b XX:XX:XX:XX:XX --char-write-req --handle=0x003f --value=2424242a008080
  Characteristic Write Request failed: Attribute can't be written
  </code></pre>
  
  <p>First command is an authentication with PIN 0000 0000 and this Looks like it is working..
  The second command failed, but i dont know why.</p>
  
  <p>Is this possible with gatttool on non-interactive mode?</p>