BSD Signal Handling
===================
This section describes alternative signal handling functions derived
from BSD Unix. These facilities were an advance, in their time; today,
they are mostly obsolete, and supported mainly for compatibility with
BSD Unix.
There are many similarities between the BSD and POSIX signal handling
facilities, because the POSIX facilities were inspired by the BSD
facilities. Besides having different names for all the functions to
avoid conflicts, the main differences between the two are:
* BSD Unix represents signal masks as an `int' bit mask, rather than
as a `sigset_t' object.
* The BSD facilities use a different default for whether an
interrupted primitive should fail or resume. The POSIX facilities
make system calls fail unless you specify that they should resume.
With the BSD facility, the default is to make system calls resume
unless you say they should fail. Note:Interrupted Primitives.
The BSD facilities are declared in `signal.h'.