sigprocmask


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.

ERRORS
       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.
       sigsuspend(2), pthread_sigmask(3), sigsetops(3), signal(7)

COLOPHON
       This page is part of release 3.23 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                             2008-10-17                    SIGPROCMASK(2)
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