int sigdelset(sigset_t *set, int signo);
The sigdelset() function deletes the individual signal specified by signo from the signal set pointed to by set.
Applications should 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.
Upon successful completion, sigdelset() shall return 0; otherwise, it shall return -1 and set errno to indicate the error.
The sigdelset() function may fail if:
The signo argument is not a valid signal number, or is an unsupported
The following sections are informative.
COPYRIGHTPortions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .