comando docker não encontrado, embora instalado com o apt-get

Adicionando isso para referência para outras pessoas, porque me pouparia 10 minutos se essa resposta existisse.

Tentei instalar o Docker usando o ubuntu 14.0LTS virtualbox

sudo apt get install docker

No entanto, quando tento executar o Docker, ele me dá o seguinte erro

The program 'docker' is currently not installed. You can install it by typing: sudo apt-get install docker

Por que o ubuntu não está vendo o docker?

O pacote Ubuntu, dockerna verdade, refere-se a um aplicativo GUI, não à amada ferramenta DevOps que procuramos.

=== ATUALIZADO (obrigado @Scott Stensland) ===

Agora você executa o seguinte script de instalação para obter o Docker:

sudo curl -sSL https://get.docker.com/ | sh

Isso executará um script que instala a janela de encaixe. Observe a última parte do script:

If you would like to use Docker as a non-root user, you should now consider
adding your user to the "docker" group with something like:

  sudo usermod -aG docker stens

Remember that you will have to log out and back in for this to take effect!

Para atualizar o Docker, execute:

sudo apt-get update && sudo apt-get upgrade

Para obter mais detalhes sobre o que está acontecendo, consulte a documentação de instalação da janela de encaixe ou a resposta de @Scott Stensland abaixo

=== RESPOSTA OBSOLETA ===

Em vez de usar dockerusedocker.io

ou seja,

sudo apt-get install docker.io

O seguinte explica por que o nome é assim: Por que instalar o docker no ubuntu deve ser `sudo apt-get install docker.io`?

IMPORTANTE - no pacote ubuntu dockeré algo completamente diferente (evite):

problema a seguir para ver o que se houver algum pacote mencionado no docker

dpkg -l|grep docker

se apenas a correspondência estiver a seguir, você NÃO possui a janela de encaixe instalada abaixo é um pacote não relacionado

docker - Bandeja do sistema para aplicativos de docklet KDE3 / GNOME2

se você vir algo semelhante ao seguinte, você terá o docker instalado

ii docker-ce 18.06.1~ce~2.1.rc1-0~ubuntu  amd64  Docker: the open-source application container engine

NOTA - o pacote ubuntu docker.ionão está recebendo atualizações (obsoleto NÃO use)

Em vez disso, faça o seguinte: instale a versão mais recente do docker no linux executando o seguinte:

  sudo curl -sSL https://get.docker.com/ | sh
# sudo curl -sSL https://test.docker.com | sh  # get dev pipeline version

aqui está uma saída típica (ubuntu 16.04)

apparmor is enabled in the kernel and apparmor utils were already installed
+ sudo -E sh -c apt-key adv --keyserver hkp://ha.pool.sks-keyservers.net:80 --recv-keys 58118E89F3A912897C070ADBF76221572C52609D
Executing: /tmp/tmp.rAAGu0P85R/gpg.1.sh --keyserver
hkp://ha.pool.sks-keyservers.net:80
--recv-keys
58118E89F3A912897C070ADBF76221572C52609D
gpg: requesting key 2C52609D from hkp server ha.pool.sks-keyservers.net
gpg: key 2C52609D: "Docker Release Tool (releasedocker) <docker@docker.com>" 1 new signature
gpg: Total number processed: 1
gpg:         new signatures: 1
+ break
+ sudo -E sh -c apt-key adv -k 58118E89F3A912897C070ADBF76221572C52609D >/dev/null
+ sudo -E sh -c mkdir -p /etc/apt/sources.list.d
+ dpkg --print-architecture
+ sudo -E sh -c echo deb [arch=amd64] https://apt.dockerproject.org/repo ubuntu-xenial main > /etc/apt/sources.list.d/docker.list
+ sudo -E sh -c sleep 3; apt-get update; apt-get install -y -q docker-engine
Hit:1 http://repo.steampowered.com/steam precise InRelease
Hit:2 http://download.virtualbox.org/virtualbox/debian xenial InRelease                                                           
Ign:3 http://dl.google.com/linux/chrome/deb stable InRelease                                                                      
Hit:4 http://dl.google.com/linux/chrome/deb stable Release                                                                        
Hit:5 http://archive.canonical.com/ubuntu xenial InRelease                                                                        
Hit:6 http://mirror.cc.columbia.edu/pub/linux/ubuntu/archive xenial InRelease                                                     
Hit:7 http://mirror.cc.columbia.edu/pub/linux/ubuntu/archive xenial-updates InRelease                                             
Hit:8 http://ppa.launchpad.net/me-davidsansome/clementine/ubuntu xenial InRelease                                                 
Ign:9 http://repo.mongodb.org/apt/debian wheezy/mongodb-org/3.2 InRelease                                                         
Hit:10 http://mirror.cc.columbia.edu/pub/linux/ubuntu/archive xenial-backports InRelease                                          
Hit:11 http://repo.mongodb.org/apt/debian wheezy/mongodb-org/3.2 Release                                                          
Hit:12 http://mirror.cc.columbia.edu/pub/linux/ubuntu/archive xenial-security InRelease                                           
Hit:14 http://ppa.launchpad.net/numix/ppa/ubuntu xenial InRelease                                                                 
Ign:15 http://linux.dropbox.com/ubuntu wily InRelease                                                                             
Ign:16 http://repo.vivaldi.com/stable/deb stable InRelease                                                                        
Hit:17 http://repo.vivaldi.com/stable/deb stable Release                                                                          
Get:18 http://linux.dropbox.com/ubuntu wily Release [6,596 B]            
Get:19 https://apt.dockerproject.org/repo ubuntu-xenial InRelease [20.6 kB]    
Ign:20 http://packages.amplify.nginx.com/ubuntu xenial InRelease                      
Hit:22 http://packages.amplify.nginx.com/ubuntu xenial Release
Hit:23 https://deb.opera.com/opera-beta stable InRelease
Hit:26 https://deb.opera.com/opera-developer stable InRelease
Get:28 https://apt.dockerproject.org/repo ubuntu-xenial/main amd64 Packages [1,719 B]
Hit:29 https://packagecloud.io/slacktechnologies/slack/debian jessie InRelease
Fetched 28.9 kB in 1s (17.2 kB/s)
Reading package lists... Done
W: http://repo.mongodb.org/apt/debian/dists/wheezy/mongodb-org/3.2/Release.gpg: Signature by key 42F3E95A2C4F08279C4960ADD68FA50FEA312927 uses weak digest algorithm (SHA1)
Reading package lists...
Building dependency tree...
Reading state information...
The following additional packages will be installed:
  aufs-tools cgroupfs-mount
The following NEW packages will be installed:
  aufs-tools cgroupfs-mount docker-engine
0 upgraded, 3 newly installed, 0 to remove and 17 not upgraded.
Need to get 14.6 MB of archives.
After this operation, 73.7 MB of additional disk space will be used.
Get:1 http://mirror.cc.columbia.edu/pub/linux/ubuntu/archive xenial/universe amd64 aufs-tools amd64 1:3.2+20130722-1.1ubuntu1 [92.9 kB]
Get:2 http://mirror.cc.columbia.edu/pub/linux/ubuntu/archive xenial/universe amd64 cgroupfs-mount all 1.2 [4,970 B]
Get:3 https://apt.dockerproject.org/repo ubuntu-xenial/main amd64 docker-engine amd64 1.11.2-0~xenial [14.5 MB]
Fetched 14.6 MB in 7s (2,047 kB/s)
Selecting previously unselected package aufs-tools.
(Reading database ... 427978 files and directories currently installed.)
Preparing to unpack .../aufs-tools_1%3a3.2+20130722-1.1ubuntu1_amd64.deb ...
Unpacking aufs-tools (1:3.2+20130722-1.1ubuntu1) ...
Selecting previously unselected package cgroupfs-mount.
Preparing to unpack .../cgroupfs-mount_1.2_all.deb ...
Unpacking cgroupfs-mount (1.2) ...
Selecting previously unselected package docker-engine.
Preparing to unpack .../docker-engine_1.11.2-0~xenial_amd64.deb ...
Unpacking docker-engine (1.11.2-0~xenial) ...
Processing triggers for libc-bin (2.23-0ubuntu3) ...
Processing triggers for man-db (2.7.5-1) ...
Processing triggers for ureadahead (0.100.0-19) ...
Processing triggers for systemd (229-4ubuntu6) ...
Setting up aufs-tools (1:3.2+20130722-1.1ubuntu1) ...
Setting up cgroupfs-mount (1.2) ...
Setting up docker-engine (1.11.2-0~xenial) ...
Processing triggers for libc-bin (2.23-0ubuntu3) ...
Processing triggers for systemd (229-4ubuntu6) ...
Processing triggers for ureadahead (0.100.0-19) ...
+ sudo -E sh -c docker version
Client:
 Version:      1.11.2
 API version:  1.23
 Go version:   go1.5.4
 Git commit:   b9f10c9
 Built:        Wed Jun  1 22:00:43 2016
 OS/Arch:      linux/amd64

Server:
 Version:      1.11.2
 API version:  1.23
 Go version:   go1.5.4
 Git commit:   b9f10c9
 Built:        Wed Jun  1 22:00:43 2016
 OS/Arch:      linux/amd64

If you would like to use Docker as a non-root user, you should now consider
adding your user to the "docker" group with something like:

  sudo usermod -aG docker stens

Remember that you will have to log out and back in for this to take effect!

Aqui estão as instruções de instalação detalhadas subjacentes que, como você pode ver, são incluídas na técnica acima ... Acima de um liner, você pode:

https://docs.docker.com/engine/installation/linux/ubuntulinux/

Uma vez instalado, você pode ver quais pacotes do docker foram instalados emitindo

dpkg -l|grep docker

ii  docker-engine                               1.11.2-0~xenial                                     amd64        Docker: the open-source application container engine

agora as atualizações do Docker serão instaladas daqui para frente quando você emitir

sudo apt-get update
sudo apt-get upgrade

dê uma olhada

 ls -latr /etc/apt/sources.list.d/*docker*
-rw-r--r-- 1 root root 202 Jun 23 10:01 /etc/apt/sources.list.d/docker.list.save
-rw-r--r-- 1 root root  71 Jul  4 11:32 /etc/apt/sources.list.d/docker.list


cat /etc/apt/sources.list.d/docker.list

deb [arch=amd64] https://apt.dockerproject.org/repo ubuntu-xenial main

sudo apt-get install docker # DO NOT do this

é uma biblioteca diferente no ubuntu.

Use sudo apt-get install docker-cepara instalar a janela de encaixe correta.

CONFIGURAR O REPOSITÓRIO

Para o Ubuntu 14.04 / 16.04 / 16.10 / 17.04:

sudo add-apt-repository "deb [arch=amd64] \
     https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"

Para o Ubuntu 17.10:

sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu zesty stable"

Adicione a chave GPG oficial do Docker:

$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

Depois instale

$ sudo apt-get update && sudo apt-get -y install docker-ce