Как удалить пустые строки?

<?php
$filename = 'site_all_image.txt';
$input = file($filename);
$result = array_unique($input);
foreach ($result  as $value)
    {
         $fp = fopen($filename , 'a');  
         fwrite($fp, $value."\r\n");  
         fclose($fp); 
    }
?>

$filename = 'site_all_image.txt';
$input = file($filename);
$result = array_unique($input);
 
$fp = fopen($filename , 'a');
foreach ($result  as $value)
    {
         if (!empty($value)) {
           //$fp = fopen($filename , 'a');  
           fwrite($fp, $value."\r\n");  
           //fclose($fp); 
         }
    }
fclose($fp);

$filename = 'site_all_image.txt';
$input = file($filename);
$result = array_unique($input);
 
$fp = fopen('new_file.txt' , 'a');
foreach ($result  as $value)
{
    fwrite($fp, rtrim($value)."\r\n");
}
fclose($fp);

<?php
$filename = 'site_all_image.txt';
$filename1 = 'new_file.txt';
$input = file($filename);
$result = array_unique($input);
 
$fp = fopen('new_file.txt' , 'a');
foreach ($result  as $value)
{
    fwrite($fp, rtrim($value)."\r\n");
}
fclose($fp);
 
 
unlink($filename); 
rename($filename, $filename1);
?>

$fp = fopen($filename , 'w');
foreach ($result  as $value)
{
    fwrite($fp, rtrim($value)."\r\n");
}
fclose($fp);
 
//unlink($filename); 
//rename($filename, $filename1);