With the function mkdir() one can create direcotories in php. According to the manual the default permission for the mkdir() function is 0777 (NB: the zero in front means its in octal!) which means read/write and execute permissions for the owner, group and others. So the directory will be wide open. Wrong!

Most of the time – at least in my experience – the umask used on Unix/Linux systems is set to 0022. This means that the mode of the directory will be changed using this umask. This change can be calculated – as far as I understood – using this rule of thumb to calculate the permission of the directory created:

permissions mode - umask = permission of directory created

Or

0777 - 0022 = 0755

So in practice most of the time the directory will be created with the permissions set to 0755. This is kind of confusing when using mkdir() as I would understand that when I set the mode for the creation of a directory would be taking into account the current set umask.

My solution is to create a directory using mkdir() and after the succesful creation I use chmod($created_directory, 0777) to set the permission to whatever I want them to be.

This entry was posted on Friday, July 13th, 2007 at 12:36 pm and is filed under geek, php, webdev. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.