SIGNALS:
FUNDAMENTAL CONCEPTS
This chapter and next two chapters discuss signals. Although the fundamental con-
cepts are simple, our discussion is quite lengthy, since there are many details to cover.
This chapter covers the following topics:
z the various different signals and their purposes;
z the circumstances in which the kernel may generate a signal for a process, and the
system calls that one process may use to send a signal to another process;
z how a process responds to a signal by default, and the means by which a process
can change its response to a signal, in particular, through the use of a signal
handler, a programmer-defined function that is automatically invoked on
receipt of a signal;
z the use of a process signal mask to block signals, and the associated notion of
pending signals; and
z how a process can suspend execution and wait for the delivery of a signal.