exec("convert -size 20x20 xc:white -fill black -pointsize 20 -gravity center -draw \" text 0,0 \"R\" \" R.gif");
exec("convert -size 20x20 xc:white -fill black -pointsize 20 -gravity center -draw \" text 0,0 \"u\" \" u.gif");
exec("convert -size 20x20 xc:white -fill black -pointsize 20 -gravity center -draw \" text 0,0 \"b\" \" b.gif");
exec("convert -size 20x20 xc:white -fill black -pointsize 20 -gravity center -draw \" text 0,0 \"l\" \" l.gif");
exec("convert -size 20x20 xc:white -fill black -pointsize 20 -gravity center -draw \" text 0,0 \"e\" \" e.gif");
exec("convert -size 20x20 xc:white -fill black -pointsize 20 -gravity center -draw \" text 0,0 \"w\" \" w.gif");
exec("convert -size 20x20 xc:white -fill black -pointsize 20 -gravity center -draw \" text 0,0 \"s\" \" s.gif");
exec("convert -background none -gravity Center R.gif u.gif b.gif b.gif l.gif e.gif w.gif e.gif b.gif s.gif -append text_vertical.gif");

// Delete the tempory images 
$delete = array('R.gif','u.gif','b.gif','l.gif','e.gif','w.gif','s.gif'); 
foreach ($delete as $value) { 
    unlink($value); }

//Another method :

//This works by adding the line feeds \n between the letters.

exec("convert -pointsize 20 -gravity center label:T\\nE\\nX\\nT vertical_text.gif");

//With this code you can automaticaly add the \n to every character in the string.
//The last character will not have a \n

 $string="TEXT";
 for ($pos = 0; $pos < strlen($string); $pos++)
 if ( $pos != strlen($string)-1 ){
	$modified .= substr($string, $pos, 1)."\\n"; }
		
	else $modified .= substr($string, $pos, 1);
		
exec("convert -pointsize 20 -gravity center label:$modified label_vertical1.gif");