How will the container behave if ENTRYPOINT is specified but CMD is not set at runtime?

If an ENTRYPOINT is set in a Docker container but CMD is not specified, then upon container start, the command will run with default arguments if they exist, or without arguments.

ENTRYPOINT defines the main executable or command, and CMD provides default arguments for this command.

If CMD is not set, then ENTRYPOINT runs without arguments. This means the container will execute ENTRYPOINT with an empty argument list, which can lead to an error or default behavior depending on the program.

Example:

ENTRYPOINT ["/bin/echo"]
# CMD not set

When the container runs, it will execute /bin/echo with no arguments, just printing an empty line.