docker exec is missing

Question

I have ubuntu 14.04 and it is missing docker exec

sudo docker exec -it ubuntu_bash bash

I wish to run interactive bash shell in existing running docker container.

sudo docker version
Client version: 1.0.1
Client API version: 1.12
Go version (client): go1.2.1
Git commit (client): 990021a
Server version: 1.0.1
Server API version: 1.12
Go version (server): go1.2.1
Git commit (server): 990021a

Answer 1

Update docker on host.

docker exec was introduced on docker 1.3.0

Answer 2

Updating docker with

apt-get update
apt-get install docker.io 

didn't help on my system, as the ubuntu packges are quite old.

I have used

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

(as describe here: http://docs.docker.com/installation/ubuntulinux/#docker-maintained-package-installation)

and got this update

docker version
Client version: 1.4.1
Client API version: 1.16
Go version (client): go1.3.3
Git commit (client): 5bc2ff8
OS/Arch (client): linux/amd64
Server version: 1.4.1
Server API version: 1.16
Go version (server): go1.3.3
Git commit (server): 5bc2ff8

Answer 3

The Long Term Support does not go past version 1.0.x. To get newer releases, tie directly to the PPA for docker by using a channel with updates. The new package will be called lxc-docker.

Copying from the article, I get

sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 36A1D7869245C8950F966E92D8576A8BA88D21E9
sudo sh -c "echo deb https://get.docker.io/ubuntu docker main > /etc/apt/sources.list.d/docker.list
sudo apt-get update
sudo apt-get remove docker.io
sudo apt-get autoremove
sudo apt-get install lxc-docker

I removed my docker.io package and any leftovers before installing the newer release to avoid uncaught conflicts. Here's what I got when it was done.

$ docker version
Client version: 1.7.1
Client API version: 1.19
Go version (client): go1.4.2
Git commit (client): 786b29d
OS/Arch (client): linux/amd64
Server version: 1.7.1
Server API version: 1.19
Go version (server): go1.4.2
Git commit (server): 786b29d
OS/Arch (server): linux/amd64

and

$ cat /etc/*release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=14.04
DISTRIB_CODENAME=trusty
DISTRIB_DESCRIPTION="Ubuntu 14.04.3 LTS"
NAME="Ubuntu"
VERSION="14.04.3 LTS, Trusty Tahr"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 14.04.3 LTS"
VERSION_ID="14.04"
HOME_URL="http://www.ubuntu.com/"
SUPPORT_URL="http://help.ubuntu.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"