sigprocmask(2) [mojave man page]

SIGPROCMASK(2)						      BSD System Calls Manual						    SIGPROCMASK(2)

NAME

     sigprocmask -- manipulate current signal mask

SYNOPSIS

     #include <signal.h>

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

DESCRIPTION

     The sigprocmask() function examines and/or changes the current signal 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 parameter how.  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 modification.

     The system quietly disallows SIGKILL or SIGSTOP to be blocked.

RETURN VALUES

     A 0 value indicated that the call succeeded.  A -1 return value indicates an error occurred and errno is set to indicated the reason.

ERRORS

     The sigprocmask() call will fail and the signal mask will be unchanged if one of the following occurs:

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

SEE ALSO

     kill(2), sigaction(2), sigsuspend(2), sigsetops(3)

STANDARDS

     The sigprocmask() function call is expected to conform to IEEE Std 1003.1-1988 (``POSIX.1'').

BSD
								   June 4, 1993 							       BSD

sigprocmask(3)						     Library Functions Manual						    sigprocmask(3)

Name
       sigprocmask - examine and change blocked signals (POSIX)

Syntax
       #include <signal.h>

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

Description
       The system call is used to examine and/or change the calling process's signal mask. If the value of the argument set is not NULL, it points
       to a set of signals that will be used to change the currently blocked set.

       The value of the argument how indicates the manner in which the set is changed as defined by the following values, defined in <signal.h>:

       SIG_BLOCK
	      The resulting signal set is the union of the current set and the signal set pointed to by the argument set.

       SIG_UNBLOCK
	      The resulting signal set is the intersection of the current set and the complement of the signal set pointed to by the argument set.

       SIG_SETMASK
	      The resulting signal set is the signal set pointed to by the argument set.

       If the argument oset is not NULL, the previous mask is stored in the space pointed to by oset.  If the value of the argument set  is  NULL,
       the process's signal mask is unchanged; thus, the function can be used to enquire about currently blocked signals.

       The signal masks used as arguments to this function are manipulated using the functions.

       As a system restriction, SIGKILL and SIGSTOP cannot be blocked.

Return Values
       A 0 return value indicates a successful call.  A -1 return value indicates an error and errno is set to indicated the reason.

Diagnostics
       The function fails and the signal mask remains unchanged if the follow occurs:

       [EINVAL]       The value of the how argument is not equal to one of the defined values.

See Also
       kill(2), sigsetmask(2), sigvec(2), sigblock(2), sigsetops(3)

																    sigprocmask(3)