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SIGPROCMASK(2)		      System Calls Manual		SIGPROCMASK(2)

NAME
       sigprocmask -- manipulate current signal	mask

LIBRARY
       Standard	C Library (libc, -lc)

SYNOPSIS
       #include	<signal.h>

       int
       sigprocmask(int how,			const sigset_t * restrict set,
	   sigset_t * restrict oset);

DESCRIPTION
       The sigprocmask() system	call examines and/or changes the current  sig-
       nal  mask  (those signals that are blocked from delivery).  Signals are
       blocked if they are members of the current signal mask set.

       If set is not null, the action of sigprocmask() depends on the value of
       the how argument.  The signal mask is changed  as  a  function  of  the
       specified  set  and the current mask.  The function is specified	by how
       using one of the	following values from <signal.h>:

       SIG_BLOCK    The	new mask is the	union of  the  current	mask  and  the
		    specified set.

       SIG_UNBLOCK  The	 new  mask is the intersection of the current mask and
		    the	complement of the specified set.

       SIG_SETMASK  The	current	mask is	replaced by the	specified set.

       If oset is not null, it is set to the  previous	value  of  the	signal
       mask.  When set is null,	the value of how is insignificant and the mask
       remains	unset providing	a way to examine the signal mask without modi-
       fication.

       The system quietly disallows SIGKILL or SIGSTOP to be blocked.

       In threaded applications, pthread_sigmask(3) must be  used  instead  of
       sigprocmask().

RETURN VALUES
       The sigprocmask() function returns the value 0 if successful; otherwise
       the  value -1 is	returned and the global	variable errno is set to indi-
       cate the	error.

ERRORS
       The sigprocmask() system	call will fail and the signal mask will	be un-
       changed if one of the following occurs:

       [EINVAL]		  The how argument has a value other than those	listed
			  here.

SEE ALSO
       kill(2),	 sigaction(2),	sigpending(2),	sigsuspend(2),	 fpsetmask(3),
       pthread_sigmask(3), sigsetops(3)

STANDARDS
       The  sigprocmask()  system  call	 is  expected  to  conform  to ISO/IEC
       9945-1:1990 ("POSIX.1").

FreeBSD	13.2			  May 7, 2010			SIGPROCMASK(2)
NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | STANDARDS

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