setrgid(3) on FreeBSD
The text 0a76c0fc8033, as FreeBSD 3.4-RELEASE, FreeBSD 3.3-RELEASE, FreeBSD 3.2-RELEASE, FreeBSD 3.1-RELEASE, FreeBSD 3.0-RELEASE, FreeBSD 2.2.9-RELEASE, FreeBSD 2.2.8-RELEASE, FreeBSD 2.2.7-RELEASE shipped it.
set user and group ID