When would I use `--interactive` without `--tty` in a Docker container?

Question

I did some googling and have had no luck finding a case where I\'d run docker run -i some_image rather than docker run -it some_image.

If

Answer 1

Since -i keeps STDIN open even if not attached, it allows for composition (piping).
For example:

docker run ubuntu printf "line1\nline2\n" | docker run -i ubuntu grep line2 | docker run -i ubuntu sed 's/line2/line3/g'

^{(Source: issue 14221)}

Or:

$ echo hello | docker run -i busybox cat
  hello

^{(Source: issue 12401)}

Now imagine this not in front of a keyboard and being used in a script where you can actually write to the processes stdin through something better than a shell |: example integration-cli/docker_cli_attach_test.go