fwrite($fd,stripslashes($_POST['content'])); 

<?php
  if(isset($_POST['content'])) 
  { 
    $fd = @fopen(($_SERVER['DOCUMENT_ROOT'] . $_POST['filename']),"w"); 
    if(!$fd) exit("Файл отсутствует или нет прав на запись"); 

$ppp=fwrite($fd,stripslashes($_POST['content'])); 

$search  = "\r\n";
$replace = "\n";
$subject=$ppp;

$rezalt=str_replace($search,  $replace , $subject);

    fclose($fd); 
    $_GET['filename'] = $_POST['filename']; 
  } 
?> 

<form action = "test.php" method="get"> 
 &nbsp; &nbsp;Имя файла <input type="text" name="filename" value=<?php echo $_GET['filename']; ?>>
&nbsp;<input type="submit" value="Отправить" class='submit5'> 
</form> 

<?php 

  if(isset($_GET['filename'])) 
  { 
    $fd = @fopen(($_SERVER['DOCUMENT_ROOT'] . $_GET['filename']),"r"); 
    if(!$fd) exit("Файл отсутствует или нет прав на чтение"); 
    $bufer = fread($fd,filesize($_SERVER['DOCUMENT_ROOT'] . $_GET['filename'])); 
$search  = "\r\n";
$replace = "\n";
$subject=$bufer;
$rezalt=str_replace($search,  $replace , $subject);

    fclose($fd); 
    ?> 
      <form action = "test.php" method="post"> 
       &nbsp; &nbsp;<textarea cols=76 rows=10 name="content" style="width:900px; height:350px;"><?php echo $rezalt; ?></textarea>
 
        <input type="hidden" name=filename value='<?php echo $_GET['filename']; ?>'> 
         &nbsp; &nbsp;<input type="submit" name=edit value="Редактировать" class='submit5'> 
      </form> 
<?php 
  } 
?>

$fd = @fopen(($_SERVER['DOCUMENT_ROOT'] . $_POST['filename']),"w"); 
    if(!$fd) exit("Файл отсутствует"); 
$search  = "\r\n";
$replace = "\n";
$tt=$_POST['content']; 
$rez=str_replace($search,  $replace , $tt);
fwrite($rez, $_POST['content']); 
fclose($fd);