title: cannot open /dev/ttyusb0 using python and pyserial
body: <p>I am writing a python script whose purpose is to communicate with serial devices. 
  In order to do that, I am using pySerial to open the device's serial port but when i tried running the script on linux platform I couldn't open the device's serial port and got an error "Access denied". 
  I am looking for a permanent solution (I don't want to print in cmd: </p>
  
  <pre><code> sudo chmod 666 /dev/ttyUSB0    
  </code></pre>
  
  <p>each time I want to access the port). Any recommendations please?</p>