I’ve seen some people ask about making the Docker command
docker.io on Ubuntu work like it does in the examples: docker. I
found this inconvenient too, but fortunately, Ubuntu and Debian have
had a solution to this for a long time, it’s called
alternatives. In
this particular case, there is already an Ubuntu package called docker
which is why they are trying to de-conflict executable names by using
docker.io in the first place. Ironically, the original docker
package doesn’t even contain an executable named docker. Or at least
it doesn’t as of Ubuntu 14.04.
$ dpkg -L docker
/.
/usr
/usr/share
/usr/share/menu
/usr/share/menu/docker
/usr/share/doc
/usr/share/doc/docker
/usr/share/doc/docker/changelog.Debian.gz
/usr/share/doc/docker/README
/usr/share/doc/docker/copyright
/usr/share/man
/usr/share/man/man1
/usr/share/man/man1/wmdocker.1.gz
/usr/bin
/usr/bin/wmdocker
I don’t fully understand the Ubuntu/Debian policies on package and
executable naming, but perhaps the use of docker.io is unnecessary.
Regardless, those of us who aren’t concerned with building packages can
either simply soft link the docker.io command to docker or create
an alternative:
# Making a link
sudo ln /usr/bin/docker.io /usr/bin/docker
# Using Alternatives
sudo update-alternatives --install /usr/bin/docker docker \
/usr/bin/docker.io 1