1SIGPROCMASK(2)                System Calls Manual               SIGPROCMASK(2)
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NAME

6       sigprocmask - manipulate current signal mask
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SYNOPSIS

9       #include <signal.h>
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11       int
12       sigprocmask(how, set, oset)
13       int how;
14       sigset_t *set;
15       sigset_t *oset;
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17       sigset_t
18       sigmask(signum)
19       int signum;
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DESCRIPTION

22       The  sigprocmask  function  examines  and/or changes the current signal
23       mask (those signals that  are  blocked  from  delivery).   Signals  are
24       blocked if they are members of the current signal mask set.
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26       If  set  is not null, the action of sigprocmask depends on the value of
27       the parameter how.  The signal mask is changed as  a  function  of  the
28       specified  set  and the current mask.  The function is specified by how
29       using one of the following values from <signal.h>:
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31       SIG_BLOCK           The new mask is the union of the current  mask  and
32                           the specified set.
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34       SIG_UNBLOCK         The  new  mask  is  the intersection of the current
35                           mask and the complement of the specified set.
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37       SIG_SETMASK         The current mask is replaced by the specified set.
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39       If oset is not null, it is set to the  previous  value  of  the  signal
40       mask.  When set is null, the value of how is insignificant and the mask
41       remains unset providing a way to examine the signal mask without  modi‐
42       fication.
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44       The system quietly disallows SIGKILL or SIGSTOP to be blocked.
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RETURN VALUES

47       A  0  value indicated that the call succeeded.  A -1 return value indi‐
48       cates an error occurred and errno is set to indicated the reason.
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ERRORS

51       The sigprocmask call will fail and the signal mask will be unchanged if
52       one of the following occurs:
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54       EINVAL              how has a value other than those listed here.
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56       EFAULT              set or oset contain an invalid address.
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SEE ALSO

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

62       The   sigprocmask   function  call  is  expected  to  conform  to  IEEE
63       Std1003.1-1988 (``POSIX'').
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674.4 Berkeley Distribution      September 3, 1997                SIGPROCMASK(2)