How do i set the path of a file in php?

(PHP 4, PHP 5, PHP 7, PHP 8)

realpath — Returns canonicalized absolute pathname

Description

realpath(string $path): string|false

Parameters

The path being checked.

Note:

Whilst a path must be supplied, the value can be an empty string. In this case, the value is interpreted as the current directory.

Return Values

Returns the canonicalized absolute pathname on success. The resulting path will have no symbolic link, /./ or /../ components. Trailing delimiters, such as \ and /, are also removed.

realpath() returns false on failure, e.g. if the file does not exist.

Note:

The running script must have executable permissions on all directories in the hierarchy, otherwise realpath() will return false.

Note:

For case-insensitive filesystems realpath() may or may not normalize the character case.

Note:

The function realpath() will not work for a file which is inside a Phar as such path would be a virtual path, not a real one.

Note:

On Windows, junctions and symbolic links to directories are only expanded by one level.

Note: Because PHP's integer type is signed and many platforms use 32bit integers, some filesystem functions may return unexpected results for files which are larger than 2GB.

Examples

Example #1 realpath() example

chdir('/var/www/');
echo realpath('./../../etc/passwd') . PHP_EOL;

echo

The above example will output:

Example #2 realpath() on Windows

On windows realpath() will change unix style paths to windows style.

echo realpath('/windows/system32'), PHP_EOL;

echo

The above example will output:

C:\WINDOWS\System32
C:\Program Files

See Also

• basename() - Returns trailing name component of path
• dirname() - Returns a parent directory's path
• pathinfo() - Returns information about a file path

Sven Arduwie ¶

14 years ago

Because realpath() does not work on files that do not
exist, I wrote a function that does.
It replaces (consecutive) occurences of / and \\ with
whatever is in DIRECTORY_SEPARATOR, and processes /. and /.. fine.
Paths returned by get_absolute_path() contain no
(back)slash at position 0 (beginning of the string) or
position -1 (ending)
    function get_absolute_path($path) {
        $path = str_replace(array('/', '\\'), DIRECTORY_SEPARATOR, $path);
        $parts = array_filter(explode(DIRECTORY_SEPARATOR, $path), 'strlen');
        $absolutes = array();
        foreach ($parts as $part) {
            if ('.' == $part) continue;
            if ('..' == $part) {
                array_pop($absolutes);
            } else {
                $absolutes[] = $part;
            }
        }
        return implode(DIRECTORY_SEPARATOR, $absolutes);
    }
?>

A test:
    var_dump(get_absolute_path('this/is/../a/./test/.///is'));
?>
Returns: string(14) "this/a/test/is"

As you can so, it also produces Yoda-speak. :)

moreau dot marc dot web at gmail dot com ¶

2 years ago

namespace MockingMagician\Organic\Helper;

class

runeimp at gmail dot com ¶

9 years ago

Needed a method to normalize a virtual path that could handle .. references that go beyond the initial folder reference. So I created the following.
function normalizePath($path)
{
    $parts = array();// Array to build a new path from the good parts
    $path = str_replace('\\', '/', $path);// Replace backslashes with forwardslashes
    $path = preg_replace('/\/+/', '/', $path);// Combine multiple slashes into a single slash
    $segments = explode('/', $path);// Collect path segments
    $test = '';// Initialize testing variable
    foreach($segments as $segment)
    {
        if($segment != '.')
        {
            $test = array_pop($parts);
            if(is_null($test))
                $parts[] = $segment;
            else if($segment == '..')
            {
                if($test == '..')
                    $parts[] = $test;

                if(

plamen at dragiyski dot org ¶

3 years ago

realpath() is just a system/library call to actual realpath() function supported by OS. It does not work on a path as a string, but also resolves symlinks. The resulting path might significantly differs from the input even when absolute path is given. No function in this notes resolves that.

The suggestion on the realpath man page is to look for an existing parent directory. Here is an example:
    function resolvePath($path) {
        if(DIRECTORY_SEPARATOR !== '/') {
            $path = str_replace(DIRECTORY_SEPARATOR, '/', $path);
        }
        $search = explode('/', $path);
        $search = array_filter($search, function($part) {
            return $part !== '.';
        });
        $append = array();
        $match = false;
        while(count($search) > 0) {
            $match = realpath(implode('/', $search));
            if($match !== false) {
                break;
            }
            array_unshift($append, array_pop($search));
        };
        if($match === false) {
            $match = getcwd();
        }
        if(count($append) > 0) {
            $match .= DIRECTORY_SEPARATOR . implode(DIRECTORY_SEPARATOR, $append);
        }
        return $match;
    }
?>

The result will retrieve absolute path for non-existing relative path. Even if a path does not exists, there should be existing directory somewhere, for which the realpath could be obtained. If this is not within the relative path (i.e. even current working directory does not exists), getcwd() will retrieve absolute path, so some absolute path is returned (although in that case the PHP process could have huge problems).

Anonymous ¶

10 years ago

Note: If you use this to check if a file exists, it's path will be cached, and returns true even if the file is removed (use file_exists instead).

David Beck ¶

15 years ago

Here's a function to canonicalize a URL containing relative paths. Ran into the problem when pulling links from a remote page.

function canonicalize($address)
{
    $address = explode('/', $address);
    $keys = array_keys($address, '..');

    foreach(

pulstar at ig dot com dot br ¶

17 years ago

Sometimes you may need to refer to the absolute path of a file in your website instead of a relative path, but the realpath() function returns the path relative to the server's filesystem, not a path relative to your website root directory.

For example, realpath() may return something like this:

/home/yoursite/public_html/dir1/file.ext

You can't use this in an HTML document, because the web server will not find the file. To do so, you can use:

function htmlpath($relative_path) {
    $realpath=realpath($relative_path);
    $htmlpath=str_replace($_SERVER['DOCUMENT_ROOT'],'',$realpath);
    return $htmlpath;
}

echo

Jrg Wagner ¶

12 years ago

Please be aware that this function does NOT always strip a trailing slash!:

LINUX (tested with PHP 5.2.11):
---
realpath('.')
: string = "/myhttpdfolder"
realpath('./')
: string = "/myhttpdfolder"
realpath('fileadmin')
: string = "/myhttpdfolder/fileadmin"
realpath('fileadmin/')
: string = "/myhttpdfolder/fileadmin"

WINDOWS (tested with PHP 5.2.5):
---
realpath('.')
: string = "C:\\myhttpdfolder"
realpath('./')
: string = "C:\\myhttpdfolder\\"
realpath('fileadmin')
: string = "C:\\myhttpdfolder\\fileadmin"
realpath('fileadmin/')
: string = "C:\\myhttpdfolder\\fileadmin\\"

Vincent Par ¶

7 years ago

Beware of relative symbolic links like this one (ext4 file system on Ubuntu) :

    vincent@vincent:~/Bureau/dirscan$ readlink sandbox/roulant/voiture/cabriolet/ln-loop-relative
    ../..

In this case, realpath may return false :

var_dump(realpath('sandbox/roulant/voiture/cabriolet/ln-loop-relative'));
// => string(44) "/home/vincent/Bureau/dirscan/sandbox/roulant"
var_dump(realpath('sandbox/roulant/voiture/cabriolet/ln-loop-relative/moto'));
// => bool(false)
?>

But you can fix it by clearing the realpath cache, this way :

var_dump(realpath('sandbox/roulant/voiture/cabriolet/ln-loop-relative'));
clearstatcache(true);
var_dump(realpath('sandbox/roulant/voiture/cabriolet/ln-loop-relative/moto'));
// => string(49) "/home/vincent/Bureau/dirscan/sandbox/roulant/moto"
?>

imagiro ¶

11 years ago

Here is a small and handy method to calculate the relative path from $from to $to. Note: On Windows it does not work when $from and $to are on different drives.

function relativePath($from, $to, $ps = DIRECTORY_SEPARATOR)
{
  $arFrom = explode($ps, rtrim($from, $ps));
  $arTo = explode($ps, rtrim($to, $ps));
  while(count($arFrom) && count($arTo) && ($arFrom[0] == $arTo[0]))
  {
    array_shift($arFrom);
    array_shift($arTo);
  }
  return str_pad("", count($arFrom) * 3, '..'.$ps).implode($ps, $arTo);
}
?>

eion at robbmob dot com ¶

6 years ago

Be aware that realpath() doesn't work with hidden Windows UNC paths, eg  \\servername\share$\folder\blah.txt but other PHP file-functions can access that file fine.

php at keith tyler dot com ¶

10 years ago

Note that under Windows, a slash-rooted path will resolve on the local drive, and *not* necessarily C:\.

For example:

M:\>php -r "print realpath('/AUTOEXEC.BAT');"
[prints nothing, because there is no M:\AUTOEXEC.BAT]

But:

M:\>C:
C:\>php -r "print realpath('/AUTOEXEC.BAT');"
C:\AUTOEXEC.BAT

Same script, different response depending on current drive.

I'm inclined to argue that this function *should* use the value of %SystemDrive% as the "slash root" base.

Lars Scheithauer ¶

17 years ago

This function is also nice to test for security-breaches. You can forbid the script to access files below a certain directory to prevent "../../../etc/shadow" and similar attacks:

// declare the basic directory for security reasons
// Please do NOT attach a "/"-suffix !
$basedir = '/var/www/cgi-bin/scriptfolder';// compare the entered path with the basedir
$path_parts = pathinfo($_REQUEST['file_to_get']);
if (realpath($path_parts['dirname']) != $basedir) {
    /* appropriate action against crack-attempt*/
    die ('coding good - h4x1ng bad!');
}?>

The url "script.php?file_to_get=../../../etc/shadow" will now result in an error.

Leonard Challis ¶

9 years ago

When using realpath (and similar functions) remember that PHP will take in to account open_basedir restrictions. So, if you do something like:

// test.php in httpdocs folder
$path = realpath(dirname(__FILE__) . '/../application');
?>

where your open_basedir setting is set to the httpdocs folder and tmp, this will return false. You must set it to the level above (or off) for this to work.

Enzo dot Barbaguelatta at alma dot cl ¶

6 months ago

Be noticed that, one of the reasons of realtpath retuning false can be if the path does not exist, or it has permission issues, or even if security modules of your operating system (let's say, SELinux for example) avoids you checking the path.

If you're like me and you had a not very good time checking why realpath retuns false, please check these points first.