PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

Interacting with the File System
443
the directory browser, particularly if you begin to build up a complex directory structure
of content based on meaningful directory names and filenames.
You could also add to your directory listing an indication of how much space is left
for uploads by using the disk_free_space($path) function. If you pass this function a
path to a directory, it will return the number of bytes free on the disk (Windows) or the
file system (Unix) on which the directory is located.
Creating and Deleting Directories
In addition to passively reading information about directories, you can use the PHP
functions mkdir() and rmdir() to create and delete directories.You can create or delete
directories only in paths that the user the script runs as has access to.
Using mkdir() is more complicated than you might think. It takes two parameters:
the path to the desired directory (including the new directory name) and the permissions
you would like that directory to have. Here’s an example:
mkdir(“/tmp/testing”, 0777);
However, the permissions you list are not necessarily the permissions you are going to
get.The inverse of the current umask will be combined with this value using AND to get
the actual permissions. For example, if the umask is 022, you will get permissions of
0755.
You might like to reset the umask before creating a directory to counter this effect,
by entering
$oldumask = umask(0);
mkdir(“/tmp/testing”, 0777);
umask($oldumask);
This code uses the umask() function, which can be used to check and change the current
umask. It changes the current umask to whatever it is passed and returns the old
umask, or, if called without parameters, it just returns the current umask.
Note that the umask() function has no effect on Windows systems.
The rmdir() function deletes a directory, as follows:
rmdir(“/tmp/testing”);
or
rmdir(“c:\\tmp\\testing”);
The directory you are trying to delete must be empty.
Interacting with the File System
In addition to viewing and getting information about directories, you can interact with
and get information about files on the web server.You previously looked at writing to
and reading from files. A large number of other file functions are available.