POSIX signals #

Scope #

POSIX signal concept.
Signal sources: hardware exceptions, actions by processes
Signal targets: specific thread, process or process group.
Common UNIX signals
Actions to be taken in response to signals:
- signal delivery:
  - signal ignoring
  - running user-defined handler
  - executing a system action (exit, core dump+exit, continue, stop)
- signal acceptance: sigwait()
Programmatic signal generation: kill(), alarm(),…
Setting up user-defined signal handling: sigaction()
Signal mask concept and signal blocking: sigprocmask(), sigpending()
Actions to be taken in case of multiple occurences of signals.
volatile sig_atomic_t type and signal handling.
Possible side effects of asynchronous signal delivery:
- premature exit of “long” system functions (with errno==EINTR) and TEMP_FAILURE_RETRY macro.
- unpredicted behaviour of non-reentrant functions; async-safe functions.
Waiting for a signal: pause(), sigsuspend(), sigwait().
Terminal generated signals. stty