7.2 raise—send a signal

Synopsis

#include <signal.h>
int raise(int sig);

int _raise_r(void *reent, int sig);

Description
Send the signal sig (one of the macros from ‘sys/signal.h’). This interrupts your program’s normal flow of execution, and allows a signal handler (if you’ve defined one, using signal) to take control.

The alternate function _raise_r is a reentrant version. The extra argument reent is a pointer to a reentrancy structure.

Returns
The result is 0 if sig was successfully raised, 1 otherwise. However, the return value (since it depends on the normal flow of execution) may not be visible, unless the signal handler for sig terminates with a return or unless SIG_IGN is in effect for this signal.

Portability
ANSI C requires raise, but allows the full set of signal numbers to vary from one implementation to another.

Required OS subroutines: getpid, kill.