realpath

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

realpathLöst einen Pfad in einen absoluten und eindeutigen auf

Beschreibung

realpath(string $path): string|false

realpath() löst alle symbolischen Verweise, /./, /../ und mehrere aufeinanderfolgende / Zeichen, die in path enthalten sind, auf und gibt den so entstehenden absoluten Pfad zurück.

Parameter-Liste

path

Der Pfad, der aufgelöst werden soll.

Hinweis:

Der Pfad muss angegeben werden, kann allerdings auch ein leerer String sein, in diesem Fall wird dann das aktuelle Verzeichnis benutzt.

Rückgabewerte

Gibt bei Erfolg den eindeutigen und absoluten Pfadnamen zurück. Dieser wird keine symbolischen Links, /./ oder /../ mehr enthalten. Abschließende Trennzeichen wie \ und / werden ebenfalls entfernt.

realpath() gibt false zurück, wenn ein Fehler auftritt, beispielsweise wenn die Datei nicht existiert.

Hinweis:

Das ausführende Script muss alle Verzeichnisse im Pfad öffnen können (auf unixoiden Systemen wäre das das "execute" Recht). Ist dies nicht der Fall, gibt realpath() false zurück.

Hinweis:

Bei Dateisystemen, bei denen Groß-/Kleinschreibung keine Rolle spielt, kann realpath() die Schreibweise kanonisieren, oder auch nicht.

Hinweis:

Die Funktion realpath() funktioniert nicht für Dateien in einem Phar, da solche Pfade virtuelle Pfade sind, aber keine realen Pfade.

Hinweis:

Unter Windows werden Junctions und symbolische Links zu Verzeichnissen nur um eine Ebene erweitert.

Hinweis: Weil PHPs Integer Typ vorzeichenbehaftet ist und viele Platformen 32bit Integer verwenden, können einige Dateisystem-Funktionen für Dateien größer als 2GB unerwartete Ergebnisse liefern.

Beispiele

Beispiel #1 realpath()

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


echo
realpath('/tmp/') . PHP_EOL;
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

/etc/passwd
/tmp

Beispiel #2 realpath() auf Windows

Unter Windows wandelt realpath() Unix-artige Pfade in gültige Windows-Pfade um:

<?php
echo realpath('/windows/system32'), PHP_EOL;

echo
realpath('C:\Program Files\\'), PHP_EOL;
?>

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

C:\WINDOWS\System32
C:\Program Files

Siehe auch

  • basename() - Liefert den letzten Namensteil einer Pfadangabe
  • dirname() - Liefert den Pfad des übergeordneten Verzeichnisses
  • pathinfo() - Liefert Informationen über einen Dateipfad

add a note

User Contributed Notes 17 notes

up
97
Sven Arduwie
16 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)
<?php
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:
<?php
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. :)
up
41
runeimp at gmail dot com
11 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.
<?php

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(
$test == '..' || $test == '')
$parts[] = $segment;
}
else
{
$parts[] = $test;
$parts[] = $segment;
}
}
}
return
implode('/', $parts);
}
?>

Will convert /path/to/test/.././..//..///..///../one/two/../three/filename
to ../../one/three/filename
up
23
moreau dot marc dot web at gmail dot com
5 years ago
<?php

namespace MockingMagician\Organic\Helper;

class
Path
{
/**
* There is a method that deal with Sven Arduwie proposal https://www.php.net/manual/en/function.realpath.php#84012
* And runeimp at gmail dot com proposal https://www.php.net/manual/en/function.realpath.php#112367
* @param string $path
* @return string
*/
public static function getAbsolute(string $path): string
{
// Cleaning path regarding OS
$path = mb_ereg_replace('\\\\|/', DIRECTORY_SEPARATOR, $path, 'msr');
// Check if path start with a separator (UNIX)
$startWithSeparator = $path[0] === DIRECTORY_SEPARATOR;
// Check if start with drive letter
preg_match('/^[a-z]:/', $path, $matches);
$startWithLetterDir = isset($matches[0]) ? $matches[0] : false;
// Get and filter empty sub paths
$subPaths = array_filter(explode(DIRECTORY_SEPARATOR, $path), 'mb_strlen');

$absolutes = [];
foreach (
$subPaths as $subPath) {
if (
'.' === $subPath) {
continue;
}
// if $startWithSeparator is false
// and $startWithLetterDir
// and (absolutes is empty or all previous values are ..)
// save absolute cause that's a relative and we can't deal with that and just forget that we want go up
if ('..' === $subPath
&& !$startWithSeparator
&& !$startWithLetterDir
&& empty(array_filter($absolutes, function ($value) { return !('..' === $value); }))
) {
$absolutes[] = $subPath;
continue;
}
if (
'..' === $subPath) {
array_pop($absolutes);
continue;
}
$absolutes[] = $subPath;
}

return
((
$startWithSeparator ? DIRECTORY_SEPARATOR : $startWithLetterDir) ?
$startWithLetterDir.DIRECTORY_SEPARATOR : ''
).implode(DIRECTORY_SEPARATOR, $absolutes);
}

/**
* Examples
*
* echo Path::getAbsolute('/one/two/../two/./three/../../two'); => /one/two
* echo Path::getAbsolute('../one/two/../two/./three/../../two'); => ../one/two
* echo Path::getAbsolute('../.././../one/two/../two/./three/../../two'); => ../../../one/two
* echo Path::getAbsolute('../././../one/two/../two/./three/../../two'); => ../../one/two
* echo Path::getAbsolute('/../one/two/../two/./three/../../two'); => /one/two
* echo Path::getAbsolute('/../../one/two/../two/./three/../../two'); => /one/two
* echo Path::getAbsolute('c:\.\..\one\two\..\two\.\three\..\..\two'); => c:/one/two
*
*/
}
up
18
David Beck
17 years ago
Here's a function to canonicalize a URL containing relative paths. Ran into the problem when pulling links from a remote page.

<?php

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

foreach(
$keys AS $keypos => $key)
{
array_splice($address, $key - ($keypos * 2 + 1), 2);
}

$address = implode('/', $address);
$address = str_replace('./', '', $address);
}

$url = 'http://www.example.com/something/../else';
echo
canonicalize($url); //http://www.example.com/else

?>
up
8
plamen at dragiyski dot org
5 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:
<?php
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).
up
25
Anonymous
12 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).
up
10
pulstar at ig dot com dot br
19 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:

<?php

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

echo
'<img src="',htmlpath('../../relative/path/to/file.ext'),'" border=1>';

?>

It will return something like:

<img src="/dir1/relative/path/to/file.ext" border=1>
up
7
Jrg Wagner
14 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\\"
up
6
https://stackoverflow.com/users/1397947/
7 years ago
It should probably be expressly noted that tilde expansion is not performed by realpath.
up
5
Vincent Par
9 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 :

<?php
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 :

<?php
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"
?>
up
7
imagiro
13 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.

<?php
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, $arTo);
}
?>
up
3
eion at robbmob dot com
8 years ago
Be aware that realpath() doesn't work with hidden Windows UNC paths, eg \\servername\share$\folder\blah.txt but other PHP file-functions can access that file fine.
up
2
Lars Scheithauer <l dot scheithauer at gmx dot de>
19 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:

<?php

// 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.
up
2
php at keith tyler dot com
13 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.
up
2
Leonard Challis
11 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:

<?php
// 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.
up
0
belisoful at icloud dot com
1 year ago
Sven Arduwie answer is not tested and does not replicate the behavior of realpath but is a close solution.

This has been unit tested to be as close to realpath as possible but without the path having to actually exist in the system.

This takes relative paths and realizes them properly based on actual current working directory, but everything can be virtual. eg. "../someVirtualDir/./virtualFile.jpg"

<?php

public static function virtualpath($path): string
{
$path = str_replace(['/', '\\'], DIRECTORY_SEPARATOR, $path);
$len = strlen($path);
$relative = strpos($path, DIRECTORY_SEPARATOR);
if (!
$len || ($len > 0 && $path[0] == '.') || $relative !== 0) {
$path = getcwd() . DIRECTORY_SEPARATOR . $path;
}
$parts = array_filter(explode(DIRECTORY_SEPARATOR, $path), 'strlen');
$absolutes = [];
foreach (
$parts as $part) {
if (
'.' == $part) {
continue;
}
if (
'..' == $part) {
array_pop($absolutes);
} else {
$absolutes[] = $part;
}
}
return
DIRECTORY_SEPARATOR . implode(DIRECTORY_SEPARATOR, $absolutes);
}

?>
up
-2
Enzo dot Barbaguelatta at alma dot cl
2 years 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.
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