I am the original author of both fish and Crush, and I honestly don't know in what way fish interacts with the OS in a way that Crush by virtue of it's design never could.
I know that Crush currently doesn't interact very well with external commands, but I don't see where that is an inherent restriction in the design rather than a missing feature.
I know that Crush currently doesn't interact very well with external commands, but I don't see where that is an inherent restriction in the design rather than a missing feature.