verbose option for docker system prune

[realyukii]

Description

The following help output didn't have verbose option, so I propose it here

$ docker system prune --help

Usage:  docker system prune [OPTIONS]

Remove unused data

Options:
  -a, --all             Remove all unused images not just dangling ones
      --filter filter   Provide filter values (e.g. "label=<key>=<value>")
  -f, --force           Do not prompt for confirmation
      --volumes         Prune anonymous volumes

It would be nice to know what the system remove and where it is (print location path of removed data)

[thaJeztah]

I don't think the API provides this information; it returns a list of references (image, volume, network, etc) that have been removed, but the underlying paths on the filesystem (for types that are related to filesystem cleanups) are not returned. Not sure if it's even possible to return those paths for all types and situations, e.g. volumes could be associated with a specific driver, and for images, it's possible that the reference is removed, but some parts still wired up otherwise.

Do you have more information on your use-case?

[realyukii]

For background: I have half-finished docker build -t project . process, because I deliberately stop it (I have to go to school and the process is take some time to complete), so I decide to prune it and start over.

I was also told by a friend that docker can resume it and I don't need to perform system prune, but it's too late :P

anyway, I just unsure if the docker cli remove the files cleanly, is there a source about which path maintained by docker? so far the one I know is /var/lib/docker.