When you first run minecraft-server, it will create the file
%%DATADIR%%/eula.txt

You need to read the EULA, and then set:
eula=true

- To run the server, run %%PREFIX%%/bin/minecraft-server
- Configuration files can be found at %%ETCDIR%%
- Log files can be found at /var/log/minecraft-server/
- World files can be found at /var/db/minecraft-server
- Debug output files can be found at /var/log/minecraft-server/debug/
- To edit java's parameters, edit %%PREFIX%%/bin/minecraft-server

NOTE:
Users upgrading from version < 1.8 are advised to run the server to
generate new config files, and then modify them based on their existing
configuration, as most files are now JSON instead of txt. Also,