I don't like it, but you can do <foo grep bar | ... if you really want L-to-R whilst avoiding the redundant cat and its overhead. That doesn't allow grep

I don't like it, but you can do <foo grep bar | ... if you really want L-to-R whilst avoiding the redundant cat and its overhead. That doesn't allow grep to do its speed-ups though, because it's still reading stdin, not a filename.