chgrp() is a wrapper for the UNIX system utility chgrp. It allows group ownership to be changed on local files. The file argument should be an absolute path or a relative path, while the group argument can be a group name or numeric group ID.
PHP 3+, PHP 4+
The owner of the file to be included must be the PHP UID or the directory in which the file resides must be owned by the PHP UID.
If safe mode is enabled, chgrp() can only change the group ownership of files that are owned by the user running the command. In most cases, this is the user that the web server runs as.
The superuser can use chgrp() to change the group of any file, regardless of ownership, but it's not advisable to run PHP as superuser without a full understanding of the dangers.
chgrp() doesn't work on Windows platforms. If called, the function always returns a value of FALSE.
PHP Functions Essential Reference. Copyright © 2002 by New Riders Publishing (Authors: Zak Greant, Graeme Merrall, Torben Wilson, Brett Michlitsch). This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later (the latest version is presently available at http://www.opencontent.org/openpub/). The authors of this book have elected not to choose any options under the OPL. This online book was obtained from http://www.fooassociates.com/phpfer/ and is designed to provide information about the PHP programming language, focusing on PHP version 4.0.4 for the most part. The information is provided on an as-is basis, and no warranty or fitness is implied. All persons and entities shall have neither liability nor responsibility to any person or entity with respect to any loss or damage arising from the information contained in this book.