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 — ファイルが書き込み可能かどうかを調べる
filenameが存在して、かつそれが書き込み可能であれば
trueを返します。引数filenameはディレクトリ名とすることができ、
ディレクトリが書き込み可能であることを調べることが可能です。
PHP は、Web サーバーが実行されているユーザー ID('nobody' が多い) でファイルにアクセスすることを覚えておいてください。
filename調べたいファイル名。
filename が存在して書き込み可能な場合に
true を返します。
失敗したときは E_WARNING が発生します。
例1 is_writable() の例
<?php
$filename = 'test.txt';
if (is_writable($filename)) {
echo 'このファイルは書き込み可能です';
} else {
echo 'このファイルは書き込みできません';
}
?>注意: この関数の結果は キャッシュされます。詳細は、clearstatcache() を参照してください。
PHP 5.0.0 以降、この関数は、
何らかの URL ラッパーと組合せて使用することができます。
どのラッパーが stat() ファミリーをサポートしているかを調べるには
サポートするプロトコル/ラッパー を参照してください。
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