Be warned, that is_writable returns false for non-existent files, although they can be written to the queried path.
(PHP 4, PHP 5, PHP 7, PHP 8)
is_writable — Prüft, ob in eine Datei geschrieben werden kann
Gibt true zurück, wenn filename existiert und
schreibbar ist. Der Dateinamens-Parameter kann auch ein Verzeichnisname
sein, um prüfen zu können, ob ein Verzeichnis schreibbar ist.
Bedenken Sie, dass PHP mit der Benutzer-ID auf die Datei zugreift, unter der der Webserver läuft (oftmals ist dies 'nobody').
filenameDer zu prüfende Dateiname.
Gibt true zurück, wenn filename existiert und
schreibbar ist.
Im Fehlerfall wird eine E_WARNING ausgegeben.
Beispiel #1 is_writable()-Beispiel
<?php
$filename = 'test.txt';
if (is_writable($filename)) {
echo 'Die Datei kann geschrieben werden';
} else {
echo 'Die Datei kann nicht geschrieben werden';
}
?>Hinweis: Die Ergebnisse dieser Funktion werden zwischengespeichert. Weitere Details sind bei clearstatcache() zu finden.
Seit PHP 5.0.0 kann diese Funktion mit einigen URL-Wrappern benutzt werden. Schauen Sie in der Liste unter Unterstützte Protokolle und Wrapper nach, welcher Wrapper die Funktionalität von stat() unterstützt.
Be warned, that is_writable returns false for non-existent files, although they can be written to the queried path.In Linux, you might encountering an issue which is a file is not writable even tho it has 644 permission! The problem is with SELinux, just disable it or add rules to allow it.To Darek and F Dot: About group permissions, there is this note in the php.ini file:; By default, Safe Mode does a UID compare check when; opening files. If you want to relax this to a GID compare,; then turn on safe_mode_gid.safe_mode_gid = OffCheck director is writable recursively. to return true, all of directory contents must be writable<?phpfunction is_writable_r($dir) { if (is_dir($dir)) { if(is_writable($dir)){ $objects = scandir($dir); foreach ($objects as $object) { if ($object != "." && $object != "..") { if (!is_writable_r($dir."/".$object)) return false; else continue; } } return true; }else{ return false; } }else if(file_exists($dir)){ return (is_writable($dir)); }}?>It appears that is_writable() does not check full permissions of a file to determine whether the current user can write to it. For example, with Apache running as user 'www', and a member of the group 'wheel', is_writable() returns false on a file like-rwxrwxr-x root wheel /etc/some.fileRegarding you might recognize your files on your web contructed by your PHP-scripts are grouped as NOBODY you can avoid this problem by setting up an FTP-Connection ("ftp_connect", "ftp_raw", etc.) and use methods like "ftp_fput" to create these [instead of giving out rights so you can use the usual "unsecure" way]. This will give the files created not the GROUP NOBODY - it will give out the GROUP your FTP-Connection via your FTP-Program uses, too.Furthermore you might want to hash the password for the FTP-Connection - then check out:http://dev.mysql.com/doc/mysql/en/Password_hashing.htmlThis file_write() function will give $filename the write permission before writing $content to it.Note that many servers do not allow file permissions to be changed by the PHP user.<?php function file_write($filename, &$content) { if (!is_writable($filename)) { if (!chmod($filename, 0666)) { echo "Cannot change the mode of file ($filename)"; exit; }; } if (!$fp = @fopen($filename, "w")) { echo "Cannot open file ($filename)"; exit; } if (fwrite($fp, $content) === FALSE) { echo "Cannot write to file ($filename)"; exit; } if (!fclose($fp)) { echo "Cannot close file ($filename)"; exit; } } ?>The results of this function seems to be not cached :Tested on linux and windows<?phpchmod($s_pathFichier, 0400);echo'<pre>';var_dump(is_writable($s_pathFichier));echo'</pre>';chmod($s_pathFichier, 04600);echo'<pre>';var_dump(is_writable($s_pathFichier));echo'</pre>';exit;?>This function returns always false on windows, when you check an network drive.See PHP Bug https://bugs.php.net/bug.php?id=68926See https://stackoverflow.com/q/54904676