Uninstall docker in WSL Ubuntu

After my installation of docker in Windows Sous-System Linux by the command following:

sudo apt-get install docker.io

I regret and I’d like to uninstall it immediately.

The error occured !

dpkg told me that he can’t work well with the command sudo apt-get remove --purge docker.io.

Removing docker.io (17.03.2-0ubuntu2~16.04.1) ...
invoke-rc.d: could not determine current runlevel
 * Stopping Docker: docker                                                                                              No process in pidfile '/var/run/docker-ssd.pid' found running; none killed.
invoke-rc.d: initscript docker, action "stop" failed.
dpkg: error processing package docker.io (--purge):
 subprocess installed pre-removal script returned error exit status 1
dmesg: read kernel buffer failed: Function not implemented
                                                          dpkg: error while cleaning up:
 subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
 docker.io
E: Sub-process /usr/bin/dpkg returned an error code (1)

Obviously, the error is from the process of stopping the docker itself.

We can show the content of docker-ssd.pid. It told us the pid of docker daemon is 22391.

Normally, as the docker daemon hasn’t been booted, the docker daemon process will not be in the process table. So the error is that: We cannot stop a process with a pid which has never been booted.

So the uninstallation script stopped when it cannot stop the docker daemon.

To avoid the error and then uninstall the docker, we can modify the pid in docker-ssd.pid with a pid of a process which is not so important.

Okay, we can launch sleep 200.

In 200 seconds, we can run ps -ef | grep sleep to obtain the pid of process of sleep.

> ps -ef | grep sleep
inoki    25219 21212  0 19:01 tty1     00:00:00 sleep 200
inoki    25221 24653  0 19:01 tty2     00:00:00 grep --color=auto sleep

We fill docker-ssd.pid with such pid.

Okay, we uninstall docker.io.

> sudo apt-get remove docker.io
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  bridge-utils cgroupfs-mount ubuntu-fan
Use 'sudo apt autoremove' to remove them.
The following packages will be REMOVED:
  docker.io
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
1 not fully installed or removed.
After this operation, 90.2 MB disk space will be freed.
Do you want to continue? [Y/n]
(Reading database ... 76380 files and directories currently installed.)
Removing docker.io (17.03.2-0ubuntu2~16.04.1) ...
'/usr/share/docker.io/contrib/nuke-graph-directory.sh' -> '/var/lib/docker/nuke-graph-directory.sh'
invoke-rc.d: could not determine current runlevel
 * Stopping Docker: docker                                                                                       [ OK ]
Processing triggers for man-db (2.7.5-1) ...

All goes well and tout va bien!