How do you get PHP, Symlinks and FILE to work together nicely?

Question

On localhost. I have the following directory structure:

/share/www/trunk/wp-content/plugins/otherfolders

/share/www/portfolio/wp-content/symlink

Where symlink is a symbolic link to /trunk/.../plugins/. Basically, this is because I need to test multiple WordPress installs and set them up, but I don't want to have to move plugins around and copy and paste them everywhere.

However, sometimes I need to crawl up the directory tree to include a config file:

 $root = dirname(dirname(dirname(dirname(__FILE__))));
      if (file_exists($root.'/wp-load.php')) {
          // WP 2.6
          require_once($root.'/wp-load.php');
      }

The folder always resolves to:

/share/www/trunk

Even when the plugin is being executed and included in

/share/www/portfolio/.

Is it possible in PHP to include files in the share/www/portfolio directory from a script executing in a symlink to the /share/www/trunk/.../plugins directory?

While this problem only happens on my test server, I'd like to have a safely distributable solution so crawling up an extra level is not an option.

Do you know where the script where you're doing the __FILE__ business is relative to the entry point? What does $_SERVER['SCRIPT_FILENAME'] equate to in the context of your example? — Shabbyrobe, Jul 22 '10 at 02:30
Bingo. I know exactly how many directories up I need to crawl. I just needed to have the right base directory. Post the answer and the bounty is yours. — Aaron Butacov, Jul 22 '10 at 04:13
An other idea would be to use hard links instead of symlinks. Or is there a reason why you need symlinks (like other mountpoint, etc.)? — JochenJung, Jul 22 '10 at 20:26
Another option is to remove the symlink and instead mount the directory (`mount -o bind target link`). You get a behavior similar to a symlink and \_\_FILE\_\_ resolves correctly. It's a hack and certainly not always an option, but may be a viable alternative in some use-cases. Also, don't forget to add it to the fstab file, or else it will disappear after rebooting. — Michael Osl, Jul 21 '14 at 14:27

pferate · Accepted Answer · 2010-07-23T00:44:06.930

33

The problem that I see with your code is that __FILE__ resolves symlinks automatically.

From the PHP Manual on Magic Constants

... Since PHP 4.0.2, __FILE__ always contains an absolute path with symlinks resolved ...

You can try using $_SERVER["SCRIPT_FILENAME"] instead.

$root = realpath(dirname(dirname(dirname(dirname($_SERVER["SCRIPT_FILENAME"])))));
  if (file_exists($root.'/wp-load.php')) {
      // WP 2.6
      require_once($root.'/wp-load.php');
  }

Note that I added the realpath() function to the root directory. Depending on your setup, you may or may not need it.

EDIT: Use $_SERVER["SCRIPT_FILENAME"] instead of $_SERVER["PHP_SELF"] for the file system path.

edited Jul 23 '10 at 00:44

answered Jul 21 '10 at 23:11

pferate

2,067
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PHP_SELF only gives the value of the current processing file. The end result needs to be an absolute path not a URI. – Aaron Butacov Jul 22 '10 at 14:48
My bad... I was originally testing from the CLI. How about using $_SERVER["SCRIPT_FILENAME"] instead? That worked in my environment. If that doesn't work what about prepending $_SERVER["DOCUMENT_ROOT"] to $_SERVER["PHP_SELF"]? – pferate Jul 22 '10 at 16:21
The following is the bug to your problem: https://bugs.php.net/bug.php?id=46260 Sadly, PHP won't change in this manner, which is a bug in my opinion. – Thorsten Schöning Jul 12 '15 at 19:42
Unfortunately, `$_SERVER["SCRIPT_FILENAME"]` doesn't work if the script you are executing this is included from another file. It's set to the original script that executed. This makes sense since the $_SERVER variable seems to be set up when the first script and doesn't change for any included scripts unlike magic constants. – user193130 Sep 20 '17 at 18:46
This is as good a workaround as it gets, but, unfortunately, we have to silently ignore the very invalidating warning then right [from the manual](http://php.net/manual/en/reserved.variables.server.php): _"There is no guarantee that every web server will provide any of these; servers may omit some, or provide others not listed here."_ – Sz. Nov 13 '18 at 01:13
from the command line you can use $_SERVER['PWD'] for the current directory (with resolved symlinks) and $_SERVER['PHP_SELF'] for the script name (with resolved symlinks) – Tuckbros Sep 04 '19 at 09:31

score 3 · Answer 2 · answered Nov 30 '16 at 10:05

Here is the solution to that issue: https://github.com/logical-and/symlink-detective

$root = dirname(dirname(dirname(dirname(__FILE__))));
  if (file_exists(SymlinkDetective::detectPath($root.'/wp-load.php'))) {
      // WP 2.6
      require_once(SymlinkDetective::detectPath($root.'/wp-load.php'));
  }

or you can try that

try {
  $root = dirname(dirname(dirname(dirname(__FILE__))));
  require_once SymlinkDetective::detectPath($root.'/wp-load.php', '', 
    false /* this would throw an exception if file doesn't exists */);
}
catch (Exception $e) {
  // nothing to do if file doesn't exists
}

I really don't understand why you removing my answer. I wrote solution for the issue, I gave examples on how it can be used, I wrote that answer. Try to do the same, instead of removing my post or let me know at least why? Isn't my information useful? — And, Dec 01 '16 at 10:12

score 2 · Answer 3 · answered Jun 07 '16 at 17:06

In some case its possible to change working dir and use getenv('PWD'):

$root = dirname(dirname(dirname(getenv('PWD'))));
if (file_exists($root.'/wp-load.php')) {
    // WP 2.6
    require_once($root.'/wp-load.php');
}

And change working directory before run this code:

cd /var/www/wp-content/themes/twenty_twelve/ && php script.php

score 2 · Answer 4 · answered Dec 22 '11 at 14:10

You can use this code snippet to get a path where symlinks are not resolved. If you don't have bash available, there's probably a different command you can use, but it works on linux enviroments.

I do think it's a malpractice that php resolves symlinks in FILE, since there's no way to get the path with symlinks. Otherwise we could easily get it using realpath.

Oh well.

<?php
$output = array();
exec('pwd', &$output);
define('__LINK__', $output[0].substr(__FILE__, strpos(__FILE__, DIRECTORY_SEPARATOR)));
?>

'pwd' returns value depends on current working dir; To work propertly you should change working directiry first: cd /var/www/wp-content/themes/twenty_twelve/ && php script.php — AndreyP, Jun 07 '16 at 16:57

score 0 · Answer 5 · answered Jul 11 '10 at 05:09

If I were trying to solve this, I'd split __FILE__ along the path bits and create a SplFileInfo for each along the way, test with isDir and isLink, then try to determine how to handle reconstruction of the path once it's known to be different than expected so you can pull from the right directory. (If you're more of a procedural type, there's is_dir and is_link.)

That being said, I think you've already disqualified this solution. Maybe the tools are smart enough to do it for you. Try comparing the result of getRealPath to getPath? getRealPath expressly says that it resolves symlinks, while getPath doesn't expressly say that.

Even then, this sniffing might not be safe on client sites, depending on who the host is. I've seen some pretty creative shared hosting filesystem setups. You could add a check to php_uname and pull out the hostname of the machine, and if it isn't your dev box, don't do the extra work.

Unfortunately, `getRealPath` and `getPath` all output the `/trunk/` directory. — Aaron Butacov, Jul 11 '10 at 20:22

score 0 · Answer 6 · answered Jul 19 '10 at 15:31

The PHP interpreter resolves symlinks before it processes them. You can do this yourself with the readlink function. PHP resolves the links because it's more efficient for *_once functions and code caches like APC, Xcache etc.

What you propably need is another way to find where a particular installation stores it's files. I'd recommend using {$_SERVER['DOCUMENT_ROOT']}/wp-content/wp-load.php assuming /share/www/portfolio is the document root.

The document root is unfortunately /share/www/ – Aaron Butacov Jul 20 '10 at 14:30 — Aaron Butacov, Jul 20 '10 at 14:30

score 0 · Answer 7 · edited Aug 29 '22 at 10:51

None of the suggested solutions worked in all these environments, CLI, PHPUNIT, WebServer.

What I ended up with was defining a variable for my project's root.

define( 'ABSPATH', __DIR__ . '/' );

And then used it in my symlinked plugins.

This may not be what you can always do but if it's okay with your use case it definitely works everywhere!

eg:

require_once(ABSPATH .'/wp-load.php');

If you are using WordPress this is already defined and you can just use it!

score 0 · Answer 8 · answered Mar 23 '23 at 18:49

For anyone stuck on this because you were using __DIR__ inside of a symbolically-linked file, (symlinked), then convert it to a DOT '.' relative instead.

E.g.

require_once __DIR__ . '/vendor/autoload.php';

Becomes

require_once './vendor/autoload.php';

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