title: How to control/check gpio states with shell commands (at91sam9260 board)
body: <p>I need to write a script that controls and checks the gpio states.</p>
  
  <p>I have been trying for a while to find a way to do it, but I didn't succeed.</p>
  
  <p>Here is for the details : 
  I use an at91sam9260 board with a Linux kernel 2.6.27 embedded in it.</p>
  
  <p>I see the /dev/gpio device 
  I tried some commands like cat /dev/gpio OR echo 1> /dev/gpio but it did not give me any result ( except an error message for the first command)</p>
  
  <p>I also tried to create /dev/gpio0 .. to /dev/gpio31 (with the makedev command before recompiling the CRAMFS filesystem, but I did not get more results.</p>
  
  <p>Does someone know how to check these gpio states and set/clear some of them ?</p>
  
  <p>More generally, Is there an easy way to find out the proper shell commands for a particular device just by looking at the driver source files ?</p>