TF_SHELL_USES
sigtraps[SIGWINCH].flags |= TF_SHELL_USES;
sigtraps[tt_sigs[i]].flags |= TF_SHELL_USES;
else if (p->flags & TF_SHELL_USES) {
sigtraps[SIGCHLD].flags |= TF_SHELL_USES;
sigtraps[SIGALRM].flags |= TF_SHELL_USES;