comando docker no encontrado aunque esté instalado con apt-get

Agregar esto como referencia para otros porque me habría ahorrado 10 minutos si tal respuesta existiera.

Intenté instalar Docker usando ubuntu 14.0LTS virtualbox

sudo apt get install docker

Sin embargo, cuando intento ejecutar Docker me da el siguiente error

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

¿Por qué ubuntu no ve Docker?

El paquete de Ubuntu en dockerrealidad se refiere a una aplicación GUI, no a la querida herramienta DevOps que buscamos.

=== ACTUALIZADO (gracias @Scott Stensland) ===

Ahora ejecuta el siguiente script de instalación para obtener Docker:

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

Esto ejecutará un script que instala la ventana acoplable. Tenga en cuenta la última parte del guión:

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 actualizar Docker, ejecute:

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

Para obtener más detalles sobre lo que está sucediendo, consulte la documentación de instalación de la ventana acoplable o la respuesta de @Scott Stensland a continuación

=== RESPUESTA OBSOLETA ===

En lugar de usar el dockerusodocker.io

es decir,

sudo apt-get install docker.io

A continuación se explica por qué se llama así: ¿Por qué instalar docker en ubuntu debería ser `sudo apt-get install docker.io`?

IMPORTANTE: el paquete ubuntu dockeres algo completamente diferente (evítelo):

siguiente problema para ver qué sucede si hay paquetes que menciona Docker

dpkg -l|grep docker

si solo hay una coincidencia, entonces NO tiene docker instalado a continuación, es un paquete no relacionado

docker: bandeja del sistema para aplicaciones de base KDE3 / GNOME2

si ve algo similar a lo siguiente, entonces tiene instalada la ventana acoplable

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

NOTA: el paquete ubuntu docker.iono recibe actualizaciones (obsoleto NO lo use)

En cambio, haz esto: instale la última versión de Docker en Linux ejecutando lo siguiente:

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

Aquí hay una salida 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!

Aquí están las instrucciones de instalación detalladas subyacentes que, como puede ver, se incluyen en la técnica anterior ... Arriba de un revestimiento le da lo mismo que:

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

Una vez instalado, puede ver qué paquetes de Docker se instalaron emitiendo

dpkg -l|grep docker

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

ahora las actualizaciones de Docker se instalarán en el futuro cuando emita

sudo apt-get update
sudo apt-get upgrade

echa un vistazo a

 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

es una biblioteca diferente en ubuntu.

Use sudo apt-get install docker-cepara instalar la ventana acoplable correcta.

CONFIGURAR EL REPOSITORIO

Para 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 Ubuntu 17.10:

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

Agregue la clave GPG oficial de Docker:

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

Luego instalar

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