root@iZ28fzgygdiZ:~# docker pull rails
FATA[0000] Cannot connect to the Docker daemon. Is 'docker -d' running on this host?

于是我又docker -d

root@iZ28fzgygdiZ:~# docker -d
INFO[0000] +job serveapi(unix:///var/run/docker.sock)
INFO[0000] Listening for HTTP on unix (/var/run/docker.sock)
INFO[0000] +job init_networkdriver()
Could not find a free IP address range for interface 'docker0'. Please configure its address manually and run 'docker -b docker0'
INFO[0000] -job init_networkdriver() = ERR (1)
FATA[0000] Could not find a free IP address range for interface 'docker0'. Please configure its address manually and run 'docker -b docker0'

于是我又docker -b docker0, 结果貌似 no command found 了。。

root@iZ28fzgygdiZ:~# docker -b docker0
Usage: docker [OPTIONS] COMMAND [arg...]

A self-sufficient runtime for linux containers.