> `tail -f | grep` is like `vim | grep` or `rogue | grep`

I think this position is user-hostile.

`vim` and `rogue` are fully user-interactive programs. The same is not true of `tail -f`, which by default appears to users as a stream of lines.

I understand why, at a technical level, `tail -f | grep` doesn't work in the way that's expected here. But it should! At least, when invoked from a user-interactive shell session -- in that context, a "chunk of data" is clearly expected to be a newline-delimited line, not a buffer of some implicitly-defined size.

In fact, `tail -f | grep` works the way they expect. What doesn’t work is `tail -f | grep | grep`.

It’s hard to argue that grep isn’t supposed to work like this when grep tries to work like this. It’s not a fundamental tension, it’s just that isatty(stdout) doesn’t always tell you when you’re running in an interactive terminal.