How to override the default command in a Docker image using the "docker run --entrypoint" command?

Each Docker image has default command defined as the "ENTRYPOINT" which will run automatically when you start the container created from the image.

But you can override it with the "docker run --entrypoint" command.

1. Continue with the "microsoft/dotnet-samples" image. It has the default command defined as "dotnet dotnetapp.dll".

2. Run it with default command overrided as "CMD":

C:\fyicenter> docker run --name windows --entrypoint cmd
   --tty --interactive microsoft/dotnet-samples

Microsoft Windows [Version 10.0.14393]
(c) 2016 Microsoft Corporation. All rights reserved.

C:\app>dir
      725 dotnetapp.deps.json
    9,216 dotnetapp.dll
      744 dotnetapp.pdb
      154 dotnetapp.runtimeconfig.json
    4,608 utils.dll
      712 utils.pdb

C:\app>

3. Open another window and connect to the container interactive running the CMD shell:

C:\fyicenter> docker exec --tty --interactive windows cmd

C:\>dir
...

Ok, we are able to override the default command defined in the image and run the "CMD" command interactively. This gives us a chance to keep the container running so that we can connect to it with "CMD" shell to explore and troubleshoot the container.

⇒ Commands Available on Windows Container

⇐ "docker run microsoft/dotnet-samples" - Test Run

⇑ Building Docker Images for Windows

⇑⇑ Docker Container Platform - Tutorials