Attempts to change the group of the file filename to group.
Only the superuser may change the group of a file arbitrarily; other users may change the group of a file to any group of which that user is a member.
Path to the file.
A group name or number.
Returns true on success or false on failure.
This function will not work on remote files as the file to be examined must be accessible via the server's filesystem.
On Windows, this function fails silently when applied on a regular file.