Why can't PHP create a directory with 777 permissions?

问题

I\'m trying to create a directory on my server using PHP with the command:

mkdir(\"test\", 0777);

But it doesn\'t give full permissions, only these:

rwxr-xr-x

回答1:

The mode is modified by your current umask, which is 022 in this case.

The way the umask works is a subtractive one. You take the initial permission given to mkdir and subtract the umask to get the actual permission:

  0777
- 0022
======
  0755 = rwxr-xr-x.

If you don't want this to happen, you need to set your umask temporarily to zero so it has no effect. You can do this with the following snippet:

$oldmask = umask(0);
mkdir("test", 0777);
umask($oldmask);

The first line changes the umask to zero while storing the previous one into $oldmask. The second line makes the directory using the desired permissions and (now irrelevant) umask. The third line restores the umask to what it was originally.

See the PHP doco for umask and mkdir for more details.

回答2:

The creation of files and directories is affected by the setting of umask. You can create files with a particular set of permissions by manipulating umask as follows :-

$old = umask(0);
mkdir("test", 0777);
umask($old);

回答3:

Avoid using this function in multithreaded webservers. It is better to change the file permissions with chmod() after creating the file.

Example:

$dir = "test";
$permit = 0777;

mkdir($dir);
chmod($dir, $permit);

回答4:

Probably, your umask is set to exclude those

回答5:

For those who tried

mkdir('path', 777);

and it did not work.

It is because, apparently, the 0 preceding the file mode is very important which tells chmod to interpret the passed number as an Octal instead of a decimal.

Reference

Ps. This is not a solution to the question but only an add-on to the accepted anwser

来源：https://stackoverflow.com/questions/3997641/why-cant-php-create-a-directory-with-777-permissions