ttyflg
if ((flags & ttyflg) == 0)
if ((flags & (forcexit | forked | errflg | ttyflg)) != ttyflg)
if ((flags & ttyflg) && (++cnt % 10))
if (flags & ttyflg)
flags &= ~ttyflg;
if (t == NULL && flags & ttyflg)
flags |= ttyflg | prompt;
int rflag = ttyflg;