title: store Os.system result in variable
body: <p>hello guys i'm wondering how to store <code>os.system</code> result in variable </p>
  
  <p>as we know it's return 0</p>
  
  <p>so i'm wondering what i should do to store the result </p>
  
  <p>and second question : how to get ip in Linux  [ somebody will suggest <code>ifconfig</code>] but <code>ifconfig</code> show so many result i just wana the <code>IP</code>  </p>