sigprocmask(2) [freebsd man page]

SIGPROCMASK(2)						      BSD 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 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 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 modification.

     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
     indicate the error.

ERRORS

     The sigprocmask() system call will fail and the signal mask will be unchanged 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'').

BSD
								    May 7, 2010 							       BSD

SIGPROCMASK(2)						     Linux Programmer's Manual						    SIGPROCMASK(2)

NAME

       sigprocmask - examine and change blocked signals

SYNOPSIS

       #include <signal.h>

       int sigprocmask(int how, const sigset_t *set, sigset_t *oldset);

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

       sigprocmask(): _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _POSIX_SOURCE

DESCRIPTION

       sigprocmask()  is  used to fetch and/or change the signal mask of the calling thread.  The signal mask is the set of signals whose delivery
       is currently blocked for the caller (see also signal(7) for more details).

       The behavior of the call is dependent on the value of how, as follows.

       SIG_BLOCK
	      The set of blocked signals is the union of the current set and the set argument.

       SIG_UNBLOCK
	      The signals in set are removed from the current set of blocked signals.  It is permissible to attempt to unblock a signal  which	is
	      not blocked.

       SIG_SETMASK
	      The set of blocked signals is set to the argument set.

       If oldset is non-NULL, the previous value of the signal mask is stored in oldset.

       If set is NULL, then the signal mask is unchanged (i.e., how is ignored), but the current value of the signal mask is nevertheless returned
       in oldset (if it is not NULL).

       The use of sigprocmask() is unspecified in a multithreaded process; see pthread_sigmask(3).

RETURN VALUE

       sigprocmask() returns 0 on success and -1 on error.  In the event of an error, errno is set to indicate the cause.

ERRORS

       EFAULT the set or oldset argument points outside the process's allocated address space.

       EINVAL The value specified in how was invalid.

CONFORMING TO

       POSIX.1-2001.

NOTES

       It is not possible to block SIGKILL or SIGSTOP.	Attempts to do so are silently ignored.

       Each of the threads in a process has its own signal mask.

       A child created via fork(2) inherits a copy of its parent's signal mask; the signal mask is preserved across execve(2).

       If SIGBUS, SIGFPE, SIGILL, or SIGSEGV are generated while they are blocked, the result is undefined, unless the	signal	was  generated	by
       kill(2), sigqueue(3), or raise(3).

       See sigsetops(3) for details on manipulating signal sets.

SEE ALSO

       kill(2), pause(2), sigaction(2), signal(2), sigpending(2), sigsuspend(2), pthread_sigmask(3), sigqueue(3), sigsetops(3), signal(7)

COLOPHON

       This  page is part of release 3.53 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2013-04-19							    SIGPROCMASK(2)