> What happens if I make a shell that does expansion slightly diffrently to the existing shells? That can't work well? We have different shells with different

> What happens if I make a shell that does expansion slightly diffrently to the existing shells? That can't work well? We have different shells with different expansions (and a myriad other differences) and it doesn't work well. In practice, the result is that people write bash scripts, not shell scripts. (Though they often don't know, and so use #!/bin/sh anyway, and so the scripts break whenever the default shell isn't bash.)