Using a Docker image
This guide page describes how to use a Docker image once you have one. This will outline running an image and providing commands which are executed inside.
Once you have a Docker image you will want to do something with it. The command
for using an image is
docker run with two arugments: the name of the image
and the command you want to run. A simple example to list the contents of the
busybox image using the
ls command is:
docker run busybox ls
This uses the common Linux command
ls and you should have seen the names of
the all directories in
busybox image. A command can also be given arguments.
For example you can list the contents of the
/bin directory in the
image by giving the name of the directory as an additional argument to
docker run busybox ls /bin
Remember because images can be thought of as 'boxes' of data and software, the
ls command is running inside the container and not on your computer.
Therefore the list of directories you see, are those inside the image and not
on your computer. You can easily compare the two by listing the contents of
We can also illustrate this further with the
uname command. The command below
will print out information about your operating system and then about the
operating system inside the image. This is an important point to remember
running a Docker image is creates a separate environment from the one you are
using on your computer.
uname -a docker run busybox uname -a
busyboximage that waits for 30 seconds using the
busyboximage that waits for 30 seconds using
sleepagain, but this time also include the docker flag
--detach. What is the difference when compared the last command?