title: gpio programming in c for wandboard
body: <p>How i can access gpio wandboard in c?</p>
  <p>
  I have a wandboard with ubuntu 14.04 and a wanted access our gpio in my c program.
  I can access in shell script, and i can put my script in my c code, but i wanted a mode of access the gpio directly my c code, without using shell command. 
  </p>
  <p>this is my shell command</p>
  <pre><code>echo 91 &gt; /sys/class/gpio/export
  echo out &gt; /sys/class/gpio/gpio91/direction
  echo 1 &gt; /sys/class/gpio/gpio91/value
  echo 0 &gt; /sys/class/gpio/gpio91/value
  </code></pre>