PHP lock text file for editing?

Question

I've got a form that writes its input to a textfile. Would it be possible to lock a text file for editing, and perhaps give a friendly message "the file is edited by another user, please try again later."

I'd like to avoid conflicts if the file has multiple editors at the same time.

Here's how the entry is currently added.

$content = file_get_contents("./file.csv");
$fh = fopen("./file.csv", "w");
fwrite($fh, $date_yy . '-' . $date_mm . '-' . $date_dd . '|' . $address . '|' . $person . '|' . $time_hh . ':' . $time_mm);
fwrite($fh, "\n" . $content);
fclose($fh);

Any thoughts?

Answer 1

You can use flock() function to lock the file. For more see this

Something like:

   <?php

      $content = file_get_contents("./file.csv");
      $fp = fopen("./file.csv", "w"); // open it for WRITING ("w")
      if (flock($fp, LOCK_EX)) 
      {
      // do your file writes here
      fwrite($fh, $date_yy . '-' . $date_mm . '-' . $date_dd . '|' . $address . '|' .  $person . '|' . $time_hh . ':' . $time_mm);
      fwrite($fh, "\n" . $content);
      fclose($fh);
      flock($fh, LOCK_UN); // unlock the file
      } 
   ?>