Changing File Permissions by php

Use chmod( ) to change the permissions of a file: 

chmod('/home/user/secrets.txt',0400);

Use chown( ) to change a file's owner and chgrp( ) to change a file's group:

<?php 

chown('/tmp/myfile.txt','sklar');           // specify user by name
chgrp('/home/sklar/schedule.txt','soccer'); // specify group by name

chown('/tmp/myfile.txt',5001);              // specify user by uid
chgrp('/home/sklar/schedule.txt',102); 

 // specify group by gid

?> 

The permissions passed to chmod( ) must be specified as an octal number.

The superuser can change the permissions, owner, and group of any file. Other users are restricted. They can change only the permissions and group of files that they own, and can't change the owner at all. Nonsuperusers can also change only the group of a file to a group they belong to.

The functions chmod( ), chgrp( ), and chown( ) don't work on Windows.