title: What is the purpose of "io.popen" function?
body: <p>I'm using an iOS application called AutoTouch. This app uses scripts based on Lua language. The developers of AutoTouch included the possibilty to call io.popen function, however I can't find any &quot;understandable&quot; examples of its use.</p>
  <p>For example, I found this description:</p>
  <blockquote>
  <pre><code>io.popen(prog[,mode])
  </code></pre>
  <p>Starts program prog in a separated process   and returns a file handle that you can use to read data from this program (if mode is &quot;r&quot;, the default) or to write data to this program (if mode is &quot;w&quot;).</p>
  </blockquote>
  <p>Does it mean that with the help of this function it's possible to use any command or application that is accessible through regular iOS terminal (on jailbroken system)?</p>
  <p>The reason I'm asking is because I would like to copy a screenshot that is kept in AutoTouch default folder to the Camera Roll folder. I thought I could somehow use the commands of Terminal to do that.</p>