how to Design Rule Check an Eagle file in a git hook?
I can execute commands from the cmd in windows when i browse to :[eagle-path]\bin. Tried with eagle 5 and 7.5.
The command for ERC is
eagle -C "erc;" [your schematic.sch]

When i remember correctly than -C is for command.

The help section found in the installation directory or in the gui is your friend here. You are searching for commando options.