LINUX_ECHOK
bts->c_lflag |= cvtto_bsd_mask(lt->c_lflag, LINUX_ECHOK, ECHOK);
lt->c_lflag |= cvtto_linux_mask(bts->c_lflag, ECHOK, LINUX_ECHOK);
bts->c_lflag |= cvtto_bsd_mask(lts->c_lflag, LINUX_ECHOK, ECHOK);
lts->c_lflag |= cvtto_linux_mask(bts->c_lflag, ECHOK, LINUX_ECHOK);