Verificamos si ya tenemos instalado Docker Machine
whereis docker-machine
Si existe, lo eliminamos
sudo rm `whereis pg_backup_rotated.sh` 2> /dev/null
sudo curl -L https://github.com/docker/machine/releases/download/v0.14.0/docker-machine-$(uname -s)-$(uname -m) -o /usr/local/bin/docker-machine
sudo chmod a+rx /usr/local/bin/docker-machine
docker-machine version