For each signal number, a disposition determines what happens when that signal is caught. SIG_DFL selects the platform’s default handler; SIG_IGN ignores the signal. A program can instead install its own handler with signal(). section 19.6
Resetting a handler
A parser’s handler receives a signal number and switches on it. For signals outside its SIGTERM and SIGABRT provisions, it restores the default disposition, records the number, and returns to the interrupted point. A handler takes a signal number and returns no value; that limited interface does not convey where or why the signal arose. section 19.6
TAKEAWAY: Configure a disposition for a specific signal number. Platform-specific signal numbers require platform documentation and reduce C-standard portability. section 19.6
