As an example, the goal is to run container that will download things hosted on the web and run some command DURING a docker launches (using ENTRYPOINT to run the command). FROMubuntuRUN apt-get updateRUN apt-get install -y wgetRUN apt-get install -y unzipRUN apt-get install -y ffmpegRUN wget https://www.cse.fau.edu/~hari/sequences/vid-clips.zipRUN unzip vid-clips.zipENTRYPOINT ["ffmpeg" -i" clip-crf20.mp4" -c:v" libx264" -crf" 36" -c:a" copy" clip-out.mp4"]If you are not root user when you run apt-get install [package], you must confirm yes or no to installation which requires user input.

Edit log [2022-07-25 Mon] I was following “What’s A Docker Image Anyway?" 1, but found that its content is no longer true, there are new changes to metadata of docker image, so I write this blog to reflect the changes that I observed at the time of writing. docker -v Docker version 20.10.17 build 100c701 I write the following Dockerfile.