PHP Directories Changing File Permissions or Ownership

PHP Directories

Changing File Permissions or Ownership

Problem

You want to change a file’s permissions or ownership; for example, you want to prevent other users from being able to look at a file of sensitive data.

Solution

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:

       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

Discussion

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. A nonsuperuser can also change only the group of a file to a group to which the user belongs.

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