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”).

Debian                                             May 7, 2010                                    SIGPROCMASK(2)