Can a Dockerfile have more than one `CMD` instruction?

No. A container is designed to run a single primary process. If you put two `CMD` instructions in a Dockerfile, Docker will simply ignore the first one and only execute the very last one.

What is the difference between `CMD` and `ENTRYPOINT`?

Both execute at runtime. However, `CMD` acts as default arguments that the user can easily override (e.g., `docker run my-app bash` overrides the CMD with bash). `ENTRYPOINT` acts as a hardcoded executable that is much harder for the user to override. They are often used together.

Why do I need `WORKDIR`? Can't I just use `RUN cd /app`?

Every instruction in a Dockerfile runs in complete isolation. If you do `RUN cd /app` on line 2, and then `RUN touch file.txt` on line 3, line 3 will execute in the root directory, not in `/app`. `WORKDIR` changes the default directory globally for all subsequent commands.

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Dockerfile Basics

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