form_driver(3) on FreeBSD
The text bf6f50ce38cb, as FreeBSD 12.4-RELEASE, FreeBSD 12.3-RELEASE, FreeBSD 12.2-RELEASE, FreeBSD 12.1-RELEASE, FreeBSD 12.0-RELEASE, FreeBSD 11.4-RELEASE, FreeBSD 11.3-RELEASE, FreeBSD 11.2-RELEASE, FreeBSD 11.1-RELEASE, FreeBSD 11.0-RELEASE shipped it.
command-processing loop of the form system