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I want to get some specific information with docker api. In this case, I want to get the IMAGE ID that correspond to <none> of REPOSITORY with command docker images

$ docker images REPOSITORY TAG IMAGE ID CREATED SIZE <none> <none> ebeb5aebbeef 5 minutes ago 479MB build-embed latest 80636e4726f8 10 minutes ago 479MB <none> <none> a2abf2e07bc3 About an hour ago 1.38GB ubuntu 18.04 4e5021d210f6 5 weeks ago 64.2MB

I tried the command as below:

$ docker images | grep `<none>'

And get results:

<none> <none> ebeb5aebbeef 2 minutes ago 479MB <none> <none> a2abf2e07bc3 58 minutes ago 1.38GB

How can I just only get the IMAGE ID? (like ebeb5aebbeef a2abf2e07bc3)

The purpose of this question is that I want to remove <none> images with docker api, like docker rmi $(docker images | grep <none>

Thank you all

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3 Answers 3

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3

Use awk to get just the third field of the matching lines.

docker images | awk '$1 == "<none>" { print $3 }'

Don't use grep '<none>' since that can match in fields other than the REPOSITORY.

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1 Comment

Thank you for your reply. I think awk is really useful for developing in Linux
3

Use --filter option with -q option, instead of listing all images and filtering them using grep

docker images -f "dangling=true" -q
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1

The docker images command has a couple of options to do this more directly, without trying to parse apart its output.

docker images -f can filter the list of images presented on a minimal set of conditions. One of those conditions is "dangling", which is exactly those images with <none> labels. This can replace your grep command.

docker images -q prints out only the image IDs and not the rest of the line. This can replace the awk command from @Barmar's answer.

This would leave you with

docker images -f dangling=true -q

to print out the image IDs of <none> images, which is what you're after; and thereby

docker images -f dangling=true -q | xargs docker rmi

to remove them.

Also consider docker system prune which will remove dangling images, and also stopped containers and unused networks.

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Thank you for your reply. I'm rookie of docker. Your detailed comment really help me understand docker.

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