Returns an array of information about a group and FALSE on failure. If gid isn't a number then NULL is returned and an E_WARNING level error is generated.
注: As of PHP 4.2.0, members is returned as an array of member usernames in the group. Before this time it was simply an integer (the number of members in the group) and the member names were returned with numerical indices.
See also posix_getegid(), filegroup(), stat(), and safe_mode_gid.