Correct way to detach from a container without stopping it

Type Ctrl+p then Ctrl+q. It will help you to turn interactive mode to daemon mode.

See https://docs.docker.com/engine/reference/commandline/cli/#default-key-sequence-to-detach-from-containers:

Once attached to a container, users detach from it and leave it running using the using CTRL-p CTRL-q key sequence. This detach key sequence is customizable using the detachKeys property. [...]

Update: As mentioned in below answers Ctrl+p, Ctrl+q will now turn interactive mode into daemon mode.

Well Ctrl+C (or Ctrl+\) should detach you from the container but it will kill the container because your main process is a bash.

A little lesson about docker. The container is not a real full functional OS. When you run a container the process you launch take the PID 1 and assume init power. So when that process is terminated the daemon stop the container until a new process is launched (via docker start) (More explanation on the matter http://phusion.github.io/baseimage-docker/#intro)

If you want a container that run in detached mode all the time, i suggest you use

docker run -d foo

With an ssh server on the container. (easiest way is to follow the dockerizing openssh tutorial https://docs.docker.com/engine/examples/running_ssh_service/)

Or you can just relaunch your container via

docker start foo

(it will be detached by default)

I dug into this and all the answers above are partially right. It all depends on how the container is launched. It comes down to the following when the container was launched:

• was a TTY allocated (-t)
• was stdin left open (-i)

^P^Q does work, BUT only when -t and -i is used to launch the container:

[berto@g6]$ docker run -ti -d --name test python:3.6 /bin/bash -c 'while [ 1 ]; do sleep 30; done;'
b26e39632351192a9a1a00ea0c2f3e10729b6d3e22f8e0676d6519e15c08b518

[berto@g6]$ docker attach test
# here I typed ^P^Q
read escape sequence

# i'm back to my prompt
[berto@g6]$ docker kill test; docker rm -v test
test
test

ctrl+c does work, BUT only when -t (without -i) is used to launch the container:

[berto@g6]$ docker run -t -d --name test python:3.6 /bin/bash -c 'while [ 1 ]; do sleep 30; done;'
018a228c96d6bf2e73cccaefcf656b02753905b9a859f32e60bdf343bcbe834d

[berto@g6]$ docker attach test
^C

[berto@g6]$    

The third way to detach

There is a way to detach without killing the container though; you need another shell. In summary, running this in another shell detached and left the container running pkill -9 -f 'docker.*attach':

[berto@g6]$ docker run -d --name test python:3.6 /bin/bash -c 'while [ 1 ]; do sleep 30; done;'
b26e39632351192a9a1a00ea0c2f3e10729b6d3e22f8e0676d6519e15c08b518

[berto@g6]$ docker attach test
# here I typed ^P^Q and doesn't work
^P
# ctrl+c doesn't work either
^C
# can't background either
^Z

# go to another shell and run the `pkill` command above

# i'm back to my prompt
[berto@g6]$

Why? Because you're killing the process that connected you to the container, not the container itself.

If you do "docker attach "container id" you get into the container. To exit from the container without stopping the container you need to enter Ctrl+P+Q