In particular, one thing that we can't (properly) do before this commit
is consuming an infinite input stream. For example:
```
yes | grep y | head -n10
```
will give 10 "y"s in most shells, but blocks indefinitely in nu. This PR
resolves that by doing blocking I/O in threads, and reducing the `await`
calls we currently have in our pipeline code.
* Switch to using `shell`
Switch to using the shell for subprocess to enable more natural shelling out.
* Update external.rs
* This is a test with .shell() for external
* El pollo loco's PR
* co co co
* Attempt to fix windows
* Fmt
* Less is more?
Co-authored-by: Andrés N. Robalino <andres@androbtech.com>
This commit changes the way we shell out externals when using the `"$it"` argument. Also pipes per row to an external's stdin if no `"$it"` argument is present for external commands.
Further separation of logic (preparing the external's command arguments, getting the data for piping, emitting values, spawning processes) will give us a better idea for lower level details regarding external commands until we can find the right abstractions for making them more generic and unify within the pipeline calling logic of Nu internal's and external's.
