The Open Group Base Specifications Issue 8
IEEE Std 1003.1-2024
Copyright © 2001-2024 The IEEE and The Open Group

NAME

sigismember — test for a signal in a signal set

SYNOPSIS

[CX] [Option Start] #include <signal.h>

int sigismember(const sigset_t *
set, int signo); [Option End]

DESCRIPTION

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.

RETURN VALUE

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.

ERRORS

The sigismember() function may fail if:

[EINVAL]
The signo argument is not a valid signal number, or is an unsupported signal number.

The following sections are informative.

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

2.4 Signal Concepts , pthread_sigmask , sigaction , sigaddset , sigdelset , sigfillset , sigemptyset , sigpending , sigsuspend

XBD <signal.h>

CHANGE HISTORY

First released in Issue 3. Included for alignment with the POSIX.1-1988 standard.

Issue 5

The last paragraph of the DESCRIPTION was included as an APPLICATION USAGE note in previous issues.

Issue 6

The SYNOPSIS is marked CX since the presence of this function in the <signal.h> header is an extension over the ISO C standard.

End of informative text.

 

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