Use Ubuntu to run a single command

As earlier we saw how to use the busybox image, but most people are not familiar with busybox, so let's see a few examples using the Ubuntu image. We are still not building our own image at this point, just playing with a ready-made image.

The run command allows us to launch a Docker container based on an image. The --rm flag tells Docker to remove the container from ou harddisk once it stopped running. It is a good idea to do so if you don't need the conatainer any more. Otherwise the dead containers would just accumulate and take up disk space.

After the name of the image we can also provide the command line that needs to be execute. In this case echo hello is just a simple shell command.

Running this will print hello and then the conatiner will exit and it will be removed from the disk as if it never existed.

docker run --rm ubuntu:20.04 echo hello