User Contributed Notes

Keatran 01-Jul-2020 07:41
unlink works the same as the rm command on nix based loses or del command on windows, it will not resolve the file but remove the exact path given even if that path is just a link.

E.G
/var/www/test/index.php = symlink(/home/test/www/index.php)
<?php
unlink("/var/www/test/index.php");
?>
Will just delete the link, not the original file where as
<?php
unlink("/home/test/www/index.php");
?>
Will unlink the original file path and break the symlink, and allow the system to overwrite as the filesystem will not know of the file's location anymore.
llmll at gmx dot de 11-Apr-2015 09:53
On OSX, when fighting against a "Permission Denied" error, make sure, the directory has WRITE permissions for the executing php-user.

Furthermore, if you rely on ACLs, and want to delete a file or symlink, the containing directory needs to have "delete_child" permission in order to unlink things inside. If you only grant "delete" to the folder that will allow you to delete the container folder itself, but not the objects inside.
Eric 11-Aug-2014 02:17
This might seem obvious, but I was tearing my hair out with this problem - make sure the file you're trying to delete isn't currently being used. I had a script that was parsing a text file and was supposed to delete it after completing, but kept getting a permission denied error because I hadn't explicitly closed the file, hence it was technically still being "used" even though the parsing was complete.
deen804 at gmail dot com 10-Dec-2013 06:14
unlink($fileName); failed for me .
Then i tried using the realpath($fileName)  function as
unlink(realpath($fileName)); it worked

just posting it , in case if any one finds it useful .
Alex, the Marrch Ca&#39;at 26-Jun-2013 04:22
The best way to delete files by mask is as follows:
<?php
array_walk(glob('/etc/*'), 'unlink');
?>
Do not use array_map mentioned below - it's purpose is to process values in a given array AND COLLECT data returned by the callback function. So, array_map is slower and uses additional memory compared to array_walk.
anagai at yahoo dot com 06-Sep-2012 07:47
This will delete all files in a directory matching a pattern in one line of code.

<?php array_map('unlink', glob("some/dir/*.txt")); ?>
dexen dot devries at gmail dot com 31-Dec-2010 01:28
Deleted a large file but seeing no increase in free space or decrease of disk usage? Using UNIX or other POSIX OS?

The unlink() is not about removing file, it's about removing a file name. The manpage says: ``unlink - delete a name and possibly the file it refers to''.

Most of the time a file has just one name -- removing it will also remove (free, deallocate) the `body' of file (with one caveat, see below). That's the simple, usual case.

However, it's perfectly fine for a file to have several names (see the link() function), in the same or different directories. All the names will refer to the file body and `keep it alive', so to say. Only when all the names are removed, the body of file actually is freed.

The caveat:
A file's body may *also* be `kept alive' (still using diskspace) by a process holding the file open. The body will not be deallocated (will not free disk space) as long as the process holds it open. In fact, there's a fancy way of resurrecting a file removed by a mistake but still held open by a process...
federico at poisonfx dot com 06-Dec-2010 02:55
Here the simplest way to delete files with mask

<?php
   $mask = "*.jpg"
   array_map( "unlink", glob( $mask ) );
?>
gotdalife at gmail dot com 25-Sep-2008 07:04
To anyone who's had a problem with the permissions denied error, it's sometimes caused when you try to delete a file that's in a folder higher in the hierarchy to your working directory (i.e. when trying to delete a path that starts with "../").

So to work around this problem, you can use chdir() to change the working directory to the folder where the file you want to unlink is located.

<?php
    $old = getcwd(); // Save the current directory
    chdir($path_to_file);
    unlink($filename);
    chdir($old); // Restore the old working directory   
?>
PD 06-Aug-2008 05:07
I have been working on some little tryout where a backup file was created before modifying the main textfile. Then when an error is thrown, the main file will be deleted (unlinked) and the backup file is returned instead.

Though, I have been breaking my head for about an hour on why I couldn't get my persmissions right to unlink the main file.

Finally I knew what was wrong: because I was working on the file and hadn't yet closed the file, it was still in use and ofcourse couldn't be deleted :)

So I thought of mentoining this here, to avoid others of making the same mistake:

<?php
// First close the file
fclose($fp);

// Then unlink :)
unlink($somefile);
?>
chris at vibenewmedia dot com 14-Sep-2004 10:54
To delete all files of a particular extension, or infact, delete all with wildcard, a much simplar way is to use the glob function.  Say I wanted to delete all jpgs .........

<?php

foreach (glob("*.jpg") as $filename) {
   echo "$filename size " . filesize($filename) . "\n";
   unlink($filename);
}

?>