How to specify the executable program to the ENTRYPOINT instruction in DockerFile?

The ENTRYPOINT instruction has two different syntax formats.

1. Executable Program Format - Executable Program Format allows you to specify the path name of an executable program file and its parameters in a JSON array format.

ENTRYPOINT ["executable", "param1", "param2", ...]

2. Shell Command Format - Shell Command Format allows you to specify the name of a shell command and its parameters in a command line format.

ENTRYPOINT command param1 param2 ...

When you use the Shell Command Format, the specified command will be executed using "/bin/sh -c" as the actual executable program. For example:

If you specify the following in the Dockerfile:
   ENTRYPOINT echo Hello!

The container will start with:
   /bin/sh -c 'echo Hello!'

So it's better to use Executable Program Format, which gives you more direct control.

⇒ Build "sleep" Image from Alpine

⇐ Build "hello" Image from Alpine

⇑ Building Docker Image with "docker build"

⇑⇑ Docker Container Platform - Tutorials