Ubuntu – /var/log/upstart/docker.log
Boot2Docker – /var/log/docker.log
Debian, GNU/Linux – /var/log/daemon.log
CentOS6 – /var/log/daemon.log | grep docker
Fedora – journalctl -u docker.service
OpenSuSE – journalctl -u docker.service
on Centos 7
journalctl -u docker.service
nJoy 😉