sigaddset man page


This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

sigaddset — add a signal to a signal set


#include <signal.h>

int sigaddset(sigset_t *set, int signo);


The sigaddset() function adds the individual signal specified by the signo to the signal set pointed to by set.

Applications shall call either sigemptyset() or sigfillset() at least once for each object of type sigset_t prior to any other use of that object. If such an object is not initialized in this way, but is nonetheless supplied as an argument to any of pthread_sigmask(), sigaction(), sigaddset(), sigdelset(), sigismember(), sigpending(), sigprocmask(), sigsuspend(), sigtimedwait(), sigwait(), or sigwaitinfo(), the results are undefined.

Return Value

Upon successful completion, sigaddset() shall return 0; otherwise, it shall return -1 and set errno to indicate the error.


The sigaddset() function may fail if:

The value of the signo argument is an invalid or unsupported signal number.

The following sections are informative.

See Also

Section 2.4, Signal Concepts, pthread_sigmask(), sigaction(), sigdelset(), sigemptyset(), sigfillset(), sigismember(), sigpending(), sigsuspend()

The Base Definitions volume of POSIX.1‐2008, <signal.h>