Php unlink file which is in use situation?

Question

In my personal experience, you cannot delete something that's in use, I think unlink() will not work if the target file is in use, how do you handle that?

<?php unlink ("notes.txt"); // how to handle if file in use? ?>

Answer 1

unlink returns a boolean that you can use to detect if deletion was successful or not:

<?php

$file = fopen('notes.txt','w');
fwrite($file,'abc123');

$resul = unlink("notes.txt"); // ◄■■■ ATTEMPT TO DELETE OPEN FILE.
if ( $resul )
     echo "File deleted";
else echo "File NOT deleted (file in use or protected)";

fclose($file);

?>    

You might see a warning message on screen, so turn off warnings and let your code (the if($resul)) handle the problem.

Edit :

It's possible to detect whether the file is in use or it is protected by using the function is_writable, next code shows how :

<?php

$file = fopen("notes.txt","w"); // ◄■■■ OPEN FILE.
fwrite($file,"abc123");

$resul = unlink("notes.txt"); // ◄■■■ ATTEMPT TO DELETE FILE.
if ( $resul ) // ◄■■■ IF FILE WAS DELETED...
     echo "File deleted";
elseif ( is_writable( "notes.txt" ) ) // ◄■■■ IF FILE IS WRITABLE...
     echo "File NOT deleted (file in use)";
else echo "File NOT deleted (file protected)";

fclose($file);

?>    

To test previous code, open the properties of the file and set it to readonly and hidden, then run the code.