Ah, I think I see what's going on. Basically, what's in
is being interpolated twice in the pattern match. The first interpolation is going from
and then it's being interpolated again, so it's looking for a vertical tab and then 706_7-17. And the forwardslash worked because it isn't a metacharacter. Thanks. That quotemeta will be useful in the future. I'd never heard of it before.