# sigprocmask(2)

    NAME
         sigprocmask - manipulate the signal mask

    SYNOPSIS
         #include <signal.h>

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

    DESCRIPTION
         Sigprocmask() examines or manipulates the signal mask.  This mask is  the
         set  of  signals that are currently blocked.  The how argument determines
         the action  that  must  be  performed.   In  all  cases  the  signal  set
         referenced  by  oset, if not NULL, will be used to receive the old signal
         mask.  The set argument, if not NULL, will be used to set or  modify  the
         current signal mask.

         How can be one of:

         SIG_BLOCK      Add the signals referenced by set to the mask.

         SIG_UNBLOCK    Remove the signals referenced by set from the mask.

         SIG_SETMASK    Set the signal mask to the set referenced by set.

         The value of how is ignored if set is NULL.

    SEE ALSO
         sigaction(2), sigpending(2), sigsuspend(2), sigset(3).

    DIAGNOSTICS
         Returns 0 on success and -1 on error.  The error code is EFAULT for a bad
         set or oset address, or EINVAL for a bad how argument.

    AUTHOR
         Kees J. Bot (kjb@cs.vu.nl)