Docker RUN vs CMD vs ENTRYPOINT

In Docker build, the three instructions RUN , CMD and ENTRYPOINT look similar and all are instructions used in a Dockerfile to define various aspects of a Docker image. Sometimes it can easily cause confusions. Let’s discuss their differences in this article.

RUN vs CMD vs ENTRYPOINT

RUN executes commands and creates new image layers.
CMD sets the command and its parameters to be executed by default after the container is started. However CMD can be replaced by docker run command line parameters.
ENTRYPOINT configures the command to run when the container starts, similar to CMD from a functionality perspective.

Shell Format vs Exec Format

We can specify the command to be run by RUN, CMD and ENTRYPOINT in two ways: Shell format and Exec format, which have subtle differences in usage.

Shell Format

Shell format has the following form:

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Docker RUN vs CMD vs ENTRYPOINT

RUN vs CMD vs ENTRYPOINT

Shell Format vs Exec Format

Shell Format

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