sigprocmask(3P)                                   sigprocmask(3P)



     NAME
          sigprocmask - examine and change blocked signals

     SYNOPSIS
          #include <signal.h>

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

     DESCRIPTION
          sigprocmask allows the calling process to examine or change
          its signal mask.  If the value of set is not NULL, it points
          to a set of signals to be used to change the currently
          blocked set.

          The value of how indicates the manner in which the set is
          changed.  The permitted values for how are:

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

          SIG_UNBLOCK   The resulting set will be the intersection of
                        the current set and the complement of the sig-
                        nal set pointed to by set.

          SIG_SETMASK   The resulting set will be the signal set
                        pointed to by set.

          If oset is not NULL, the previous mask is stored at the lo-
          cation pointed to by set.  If the value of set is NULL, the
          value of how is ignored and the process's signal mask is un-
          changed.  When set is NULL, sigprocmask can be used to en-
          quire about currently blocked signals.

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

          SIGKILL and SIGSTOP cannot be caught or ignored.  SIGCONT
          cannot be ignored.  It is not possible to block these sig-
          nals.  This is silently enforced.

     RETURN VALUE
          Upon successful completion, 0 is returned.  Otherwise, -1 is
          returned and errno is set to indicate the error.

     ERRORS
          If the following condition occurs, sigprocmask will return
          -1 and set errno to the corresponding value.




     April, 1990                                                     1

     sigprocmask(3P)                                   sigprocmask(3P)



          [EINVAL]      The value of how is invalid.

     SEE ALSO
          sigaction(3P), sigpending(3P), sigsetops(3P),
          sigsuspend(3P).


















































     2                                                     April, 1990