Usually before doing the standard docker process like this:
docker pull epgg/eg
docker run -p 80:80 --name eg -it epgg/eg bash
You need to run sudo dockerd at the background (i.e. with terminal open).
How can I permanently run that at the background without terminal open?
No, better not run the docker daemon like that: sudo dockerd.
Depending on your Linux distribution you can use the following commands:
For running docker at startup:
sudo chkconfig docker on
For starting docker service:
sudo service docker start
These commands would work on RHEL/CentOS 6, Debian/Ubuntu.
If systemd is available on your Linux installation (for example on RHEL/CentOS 7), you could also use the following commands:
For running docker at startup:
sudo systemctl enable docker
For starting docker service:
sudo systemctl start docker
For docker engine itself , use the systemctl enable and systemctl start as mentioned above.
But I think you mean running the container in the background, it should be like this:
First run it in background:
docker run -d -p 80:80 --name eg epgg/eg
then later you can still get a bash into it:
docker exec -it eg bash