docker daemon log

It depends on your OS. Here are the few locations, with commands for few Operating Systems:

Ubuntu - /var/log/upstart/docker.log
Boot2Docker - /var/log/docker.log
Debian GNU/Linux - /var/log/daemon.log
CentOS - /var/log/daemon.log | grep docker
CoreOS - journalctl -u docker.service
Fedora - journalctl -u docker.service
Red Hat Enterprise Linux Server - /var/log/messages | grep docker
OpenSuSE - journalctl -u docker.service
OSX - ~/Library/Containers/com.docker.docker/Data/com.docker.driver.amd64-linux/log/d‌​ocker.log

其餘：

** /var/log/messages**

**journalctl -fu docker.service**