<?php

$text = " first  line... abc   
 second  is  here... def   
  <-- blank space here
 fourth  line... hi  there   

 sith  is  here....   ";

 // get rid of spaces at the beginning and end of line
 $regex = '~^\ +|\ +$~m';
 $text = preg_replace($regex, '', $text);

 // get rid of more than two consecutive spaces
$regex = '~\ {2,}~';
$text = preg_replace($regex, ' ', $text);
echo $text;

?>