I think something like this would be good, but I don’t think I’d base it on bash. Some of the things I would have are: 1. When someone writes a command like fo

I think something like this would be good, but I don’t think I’d base it on bash. Some of the things I would have are: 1. When someone writes a command like foo | bar, instead of making a single pipe from one to the next, put your own lightweight program that works a bit like pv in the middle. In the standard case this is a pretty cheap program: it just needs to call splice to move from stdin to stdout, but you could have some mechanism to eg view the data going through a pipe or the rate of data: one could tell if the program is doing anything 2. Typical interactive shell use involves writing commands, inspecting output, then modifying the commands. A notebook format may be better for that. I think I’d want some mechanism to say “these commands will generate some output. I want to inspect it then write the next stage in the pipeline so hang onto that output instead of rerunning the command.” And why not make some “interactive grep” and interactive versions of other commands so that one can get immediate feedback when modifying the regex. 3. It’s hard to know if a command will have side effects but I feel like it matters a lot. Maybe something could be done to detect it somehow.