Related problem

save collects input data in a few situations where it doesn't always need to:

Describe the solution you'd like

save should always stream ListStream input into a file instead of attempting to collect it all.

It should be possible to stream to a file slowly:

1..100 | each { |i| sleep 400ms; $i} | save -f output.txt

And watch individual lines (or batches of lines) arrive with tail --follow in another shell:

tail --follow output.txt

Additional context and details

Hat tip to this comment: #6178 (comment)