添加文本文件而不重复n1

Please Help Modification of this code should not repeat n1 When entering data into a text file Do not repeat text when you add a new message with

 <?php
    
if(isset($_POST['send'])){
    
    $n1 = trim($_POST['n1']);
    $n2 = trim($_POST['n2']);

  $fileLocation = getenv("DOCUMENT_ROOT") . "/te.txt";
  $file = fopen($fileLocation,"a");
$n1 = $_POST['n1'];
$n2 = $_POST['n2'];

  fwrite($file,$n1.'|'.$n2."
");
  fclose($file);
  
 

   }

?>

</div>

Try this,

        <?php

    if(isset($_POST['send'])){

        $n1 = trim($_POST['n1']);
        $n2 = trim($_POST['n2']);

      $fileLocation = getenv("DOCUMENT_ROOT") . "/te.txt";
      $file = fopen($fileLocation,"r+");

  $content = fread($file, filesize($fileLocation));
 echo $content;
    if(strstr($content, "|")){
          fwrite($file,$n2."
");
    }else{
      fwrite($file,$n1.'|'.$n2."
");
    }

  fclose($file);

       }

    ?>