sigprocmask(3P)                                   sigprocmask(3P)



NAME
     sigprocmask - examines and changes 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 signal 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
     location pointed to by set.  If the value of set is NULL,
     the value of how is ignored and the process's signal mask is
     unchanged.  When set is NULL, sigprocmask can be used to
     enquire 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
     signals.  This is silently enforced.

STATUS MESSAGES AND VALUES
     Upon successful completion, 0 is returned.  Otherwise, -1 is
     returned and errno is set to indicate the error.

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



January 1992                                                    1

sigprocmask(3P)                                   sigprocmask(3P)



     EINVAL
          The value of how is invalid.

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


















































2                                                    January 1992