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SIGSETOPS(3)		   Linux Programmer's Manual		  SIGSETOPS(3)

       sigemptyset, sigfillset, sigaddset, sigdelset, sigismember - POSIX sig-
       nal set operations

       #include <signal.h>

       int sigemptyset(sigset_t *set);

       int sigfillset(sigset_t *set);

       int sigaddset(sigset_t *set, int signum);

       int sigdelset(sigset_t *set, int signum);

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

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       sigemptyset(), sigfillset(), sigaddset(), sigdelset(), sigismember():

       These functions allow the manipulation of POSIX signal sets.

       sigemptyset() initializes the signal set given by set  to  empty,  with
       all signals excluded from the set.

       sigfillset() initializes set to full, including all signals.

       sigaddset()  and	 sigdelset() add and delete respectively signal signum
       from set.

       sigismember() tests whether signum is a member of set.

       Objects of type sigset_t must  be  initialized  by  a  call  to	either
       sigemptyset()  or  sigfillset()	before	being  passed to the functions
       sigaddset(), sigdelset() and  sigismember()  or	the  additional	 glibc
       functions  described  below  (sigisemptyset(),  sigandset(),  and  sig-
       orset()).  The results are undefined if this is not done.

       sigemptyset(), sigfillset(), sigaddset(), and sigdelset() return	 0  on
       success and -1 on error.

       sigismember()  returns  1  if signum is a member of set, 0 if signum is
       not a member, and -1 on error.

       On error, these functions set errno to indicate the cause of the error.

       EINVAL sig is not a valid signal.

       For  an	explanation  of	 the  terms  used   in	 this	section,   see

       |Interface			| Attribute	| Value	  |
       |sigemptyset(), sigfillset(),	| Thread safety | MT-Safe |
       |sigaddset(), sigdelset(),	|		|	  |
       |sigismember(), sigisemptyset(), |		|	  |
       |sigorset(), sigandset()		|		|	  |
       POSIX.1-2001, POSIX.1-2008.

       When creating a filled signal set, the glibc sigfillset() function does
       not include the two real-time  signals  used  internally	 by  the  NPTL
       threading implementation.  See nptl(7) for details.

   Glibc extensions
       If  the	_GNU_SOURCE  feature  test  macro  is defined, then <signal.h>
       exposes three other functions for manipulating signal sets:

       int sigisemptyset(const sigset_t *set);
       int sigorset(sigset_t *dest, const sigset_t *left,
		     const sigset_t *right);
       int sigandset(sigset_t *dest, const sigset_t *left,
		     const sigset_t *right);

       sigisemptyset() returns 1 if set contains no signals, and 0 otherwise.

       sigorset() places the union  of	the  sets  left	 and  right  in	 dest.
       sigandset() places the intersection of the sets left and right in dest.
       Both functions return 0 on success, and -1 on failure.

       These functions are nonstandard (a few other  systems  provide  similar
       functions) and their use should be avoided in portable applications.

       sigaction(2), sigpending(2), sigprocmask(2), sigsuspend(2)

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       description of the project, information about reporting bugs,  and  the
       latest	  version     of     this    page,    can    be	   found    at

Linux				  2016-03-15			  SIGSETOPS(3)