Docker Container run

Docker run is a combination of create and start a container. It first creates the container and then starts it. The docker run command first creates a writeable container layer over the specified image, and then starts it using the specified command.

Detach and Run Container in Background

To run a container in the background, we can use docker container run command with -d (detach) mode and specify the container name (or ID) as well as the command to be executed on this container. 

Syntax

$ docker container run <command>

Now, to execute the “sleep 30” command on the ubuntu container and send it to the background, simply provide -d option to run it in detached mode-

learning-ocean:~ gaurav$ docker container run -d ubuntu:14.04 sleep 30
0fbc31ed81ef0f25d245b32d040389f640ce95c58f2d541e9f81bf733e84dcde
learning-ocean:~ gaurav$ 

Docker Interactive Option (IT)

Docker allows you to run a container in interactive mode as well.

learning-ocean:~ gaurav$ docker container run -it ubuntu:14.04 /bin/bash
root@ad9f71ce3a04:/# #now i am in Container. please notice the hostname in this line
root@ad9f71ce3a04:/# hostname
ad9f71ce3a04
root@ad9f71ce3a04:/# cat /etc/os-release 
NAME="Ubuntu"
VERSION="14.04.6 LTS, Trusty Tahr"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 14.04.6 LTS"
VERSION_ID="14.04"
HOME_URL="http://www.ubuntu.com/"
SUPPORT_URL="http://help.ubuntu.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"
root@ad9f71ce3a04:/# 

So by using the above command, users get an interactive bash shell of the container. And if the user wants to come out from the container and still wants to run it in the background then simply hit [ctrl+pq] from the keyboard.