PROLOG

       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.

NAME

       sigismember — test for a signal in a signal set

SYNOPSIS

       #include <signal.h>

       int sigismember(const sigset_t *set, int signo);

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

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

       The Base Definitions volume of POSIX.1‐2017, <signal.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1-2017, Standard for Information Technology -- Portable  Operating  System  Interface
       (POSIX),  The  Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .