How do I check if a directory is writeable in PHP?

问题:

Does anyone know how I can check to see if a directory is writeable in PHP?

The function is_writable doesn't work for folders. (edit: It does work. See the accepted answer.)

回答1:

Yes, it does work for folders....

Returns TRUE if the filename exists and is writable. The filename argument may be a directory name allowing you to check if a directory is writable.

回答2:

this is the code :)

<?php 

$newFileName = '/var/www/your/file.txt';

if ( ! is_writable(dirname($newFileName))) {

    echo dirname($newFileName) . ' must writable!!!';
} else {

    // blah blah blah
}

回答3:

to be more specific for owner/group/world

$dir_writable = substr(sprintf('%o', fileperms($folder)), -4) == "0774" ? "true" : "false";

peace...

回答4:

You may be sending a complete file path to the is_writable() function. is_writable() will return false if the file doesn't already exist in the directory. You need to check the directory itself with the filename removed, if this is the case. If you do that, is_writable will correctly tell you whether the directory is writable or not. If $file contains your file path do this:

$file_directory = dirname($file);

Then use is_writable($file_directory) to determine if the folder is writable.

I hope this helps someone.

回答5:

According to the documentation for is_writable, it should just work - but you said "folder", so this could be a Windows issue. The comments suggest a workaround.

(A rushed reading earlier made me think that trailing slashes were important, but that turned out to be specific to this work around).

回答6:

stat()

Much like a system stat, but in PHP. What you want to check is the mode value, much like you would out of any other call to stat in other languages (I.E. C/C++).

http://us2.php.net/stat

回答7:

I've written a little script (I call it isWritable.php) that detects all directories in the same directory the script is in and writes to the page whether each directory is writable or not. Hope this helps.

<?php
// isWritable.php detects all directories in the same directory the script is in
// and writes to the page whether each directory is writable or not.

$dirs = array_filter(glob('*'), 'is_dir');

foreach ($dirs as $dir) {
    if (is_writable($dir)) {
        echo $dir.' is writable.<br>';
    } else {
        echo $dir.' is not writable. Permissions may have to be adjusted.<br>';
    } 
}
?>

回答8:

According to the PHP manual is_writable should work fine on directories.

回答9:

this is how I do it:

create a file with file_put_contents() and check the return value, if it is positive (number of written in Bytes) then you can go ahead and do what you have to do, if it is FALSE then it is not writable

$is_writable = file_put_contents('directory/dummy.txt', "hello");

if ($is_writable > 0) echo "yes directory it is writable";

else echo  "NO directory it is not writable";

then you can delete the dummy file by using unlink()

unlink('directory/dummy.txt');