sigprocmask(2)             DG/UX 4.30              sigprocmask(2)



     NAME
          sigprocmask - Examine and change blocked signals.

     SYNOPSIS
          #include <signal.h>

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

     DESCRIPTION
          The sigprocmask function is used to examine or change (or
          both) the calling process's signal mask.  If the value of
          the argument set is not NULL, it points to a set of signals
          to be used to change the currently blocked set.

          The value of the argument how indicates the manner in which
          the set is changed, and shall consist of one of the
          following values, as defined in the header <signal.h>.

                  Name                   Description

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

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

               SIG_SETMASK   The resulting set shall be 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 value of the argument how is not
          significant and the process's signal mask is unchanged by
          this function call; thus, the call can be used to enquire
          about currently blocked signals.

          If there are any pending unblocked signals after the call to
          the sigprocmask function, at least one of those signals
          shall be delivered before the sigprocmask function returns.

          It is not possible to block the SIGKILL and SIGSTOP signals;
          this shall be enforced by the system without causing an
          error to be indicated.

          If any of the SIGFPE, SIGILL, or SIGSEGV signals are



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     sigprocmask(2)             DG/UX 4.30              sigprocmask(2)



          generated while they are blocked, the result is undefined,
          unless the signal was generated by a call to the kill
          function or the raise function defined by the C Standard.

          If the sigprocmask function fails, the process's signal mask
          is not changed by this function call.

     RETURNS
          Upon successful completion a value of zero is returned.
          Otherwise, a value of -1 is returned and errno is set to
          indicate the error.

     ERRORS
          If any of the following conditions occur, the sigprocmask
          function shall return -1 and set errno to the corresponding
          value:

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

     SEE ALSO
          sigaction(2), <signal.h>, sigpending(2), sigsetops(3),
          sigsuspend(2)

     COPYRIGHTS
          Portions of this text are reprinted from IEEE Std 1003.1-
          1988, Portable Operating System Interface for Computer
          Environment, copyright © 1988 by the Institute of Electrical
          and Electronics Engineers, Inc., with the permission of the
          IEEE Standards Department.  To purchase IEEE Standards, call
          800/678-IEEE.

          In the event of a discrepancy between the electronic and the
          original printed version, the original version takes
          precedence.



















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