Difference between RUN and CMD in a docker file and when to use one or the other

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Which command to use to execute bash/shell commands i.e. ls -la.

When should I use CMD and where should I use RUN? 

What's the best practice about these two similar Dockerfile directives.

Can anyone help me with this?

Thanks.

Nov 16, 2018 in DevOps & Agile by Shubham
• 1,000 points
3,081 views

1 answer to this question.

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Here are the explanations for all the three commands i.e., RUN,CMD and ENTRYPOINT.

RUN :-  A Dockerfile can have many RUN steps that layer on top of one another to build the image.

CMD :- It is the command which the container executes by default when you launch the built image. A Dockerfile can only have one CMD. The CMD can be overridden when starting a container with docker run $image $other_command.

ENTRYPOINT :- It is very much similar to CMD and can modify the way a container starts an image.

I hope that the above explanation will resolve your doubts.

answered Nov 17, 2018 by Damon Salvatore
• 5,980 points

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