When you installed Docker using the command:
sudo curl -sSL https://get.docker.com/ | sh
This actually ran an automated installation script that performed multiple operations on your system. Unlike package manager installations, this method doesn't register with Debian's dpkg system, making uninstallation less straightforward.


First, stop all Docker services:
sudo service docker stop
sudo systemctl stop docker.socket

Remove Docker packages and dependencies:
sudo apt-get purge docker-ce docker-ce-cli containerd.io
sudo apt-get autoremove --purge


The automated script creates several artifacts that need manual removal:

Delete Docker files and directories:
sudo rm -rf /var/lib/docker
sudo rm -rf /var/lib/containerd
sudo rm -rf /etc/docker

Remove Docker group:
sudo groupdel docker


Check if any Docker components remain:
which docker
docker --version
ps aux | grep docker

All these commands should return no results if Docker is completely removed.


Docker provides an uninstall script you can run:
curl -sSL https://get.docker.com/ | sudo sh -s -- --uninstall


Check for remaining configurations in:
/etc/default/docker
/etc/init.d/docker
~/.docker/

Remove any found files in these locations.


For complete cleanup:
sudo reboot

When you installed Docker using the command sudo curl -sSL https://get.docker.com/ | sh, you essentially ran an automated installation script that handles multiple package management systems. This makes the uninstallation process slightly different from removing standard Debian packages.

First, let's check what Docker components were installed:

dpkg -l | grep -i docker

For Debian-based systems, use these commands:

sudo apt-get purge docker-ce docker-ce-cli containerd.io
sudo apt-get autoremove --purge

Docker leaves configuration files and runtime data even after uninstallation. Clean them with:

sudo rm -rf /var/lib/docker
sudo rm -rf /var/lib/containerd

Remove Docker-related user groups if they exist:

sudo groupdel docker

Check if any Docker processes are still running:

ps aux | grep -i docker

And verify no Docker-related packages remain:

dpkg -l | grep -i docker

The Docker installation script might have created an uninstall helper:

sudo /usr/local/bin/docker-uninstall.sh

If this exists, it will handle most of the cleanup automatically.

For Debian 7 (Wheezy), you might need additional cleanup:

sudo apt-get purge lxc-docker
sudo apt-get purge docker.io

After all these steps, perform a general cleanup:

sudo apt-get clean
sudo apt-get autoclean