sigismember - test for a signal in a signal set
The sigismember() function shall test whether the signal specified by signo is a member of the 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, sigismember() shall return 1 if the specified signal is a member of the specified set, or 0 if it is not. Otherwise, it shall return -1 and set errno to indicate the error.
The sigismember() function may fail if:
- The signo argument is not a valid signal number, or is an unsupported signal number.
Signal Concepts, pthread_sigmask, sigaction, sigaddset, sigdelset, sigfillset, sigemptyset, sigpending, sigsuspend
First released in Issue 3. Included for alignment with the POSIX.1-1988 standard.
The last paragraph of the DESCRIPTION was included as an APPLICATION USAGE note in previous issues.
The SYNOPSIS is marked CX since the presence of this function in the <signal.h> header is an extension over the ISO C standard.
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