title: whats is the meaning of 'if [ -s filename]' in shell?
body: <p>So I've 'if [ -s $fname ]' in my shell program.Can someone please tell me what it does? I searched it but there is nothing about '-s'.</p>
  
  <pre><code>if [ -s $fname ]
  then 
     echo -e "\tname\tph\t\tcity\tpin\tstate"
    cat $fname
  else
    echo -e "\nfile is empty"
   fi
  ;;
  </code></pre>
  
  <p>this is part of my code where -s is used in case you need it.Thanks!</p>