Handling Unix Signals
1. Each signal type has a system-defined default action.
abort and dump core (SIGSEGV, SIGBUS, etc.)
ignore, stop, exit, continue
2. A process may choose to block (inhibit) or ignore some signal types.
useful for synchronizing with signal handlers: inhibit signals before executing code shared with the signal handler
3. The process may choose to catch some signal types by specifying a (user mode) handler procedure.
system passes interrupted context to handler
handler may munge and/or return to interrupted context