rt_sigaction alters an action taken by a process on receipt of a particular signal. The action is specified by the sigaction structure. The previous action on the signal is saved in oact. sigsetsize should indicate the size of a sigset_t type.
rt_sigaction returns 0 on success; otherwise, rt_sigaction returns one of the errors listed in the "Errors" section.
rt_sigpending(2), rt_sigprocmask(2), rt_sigqueueinfo(2), rt_sigreturn(2), rt_sigsuspend(2), rt_sigtimedwait(2)