package org.ethereum;

import org.ethereum.cli.CLIInterface;
import org.ethereum.config.SystemProperties;
import org.ethereum.facade.Ethereum;
import org.ethereum.facade.EthereumFactory;

import java.io.IOException;
import java.net.URISyntaxException;

/**
 * @author Roman Mandeleil
 * @since 14.11.2014
 */
public class Start {

    public static void main(String args[]) throws IOException, URISyntaxException {
        CLIInterface.call(args);

        if (!SystemProperties.getDefault().blocksLoader().equals("")) {
            SystemProperties.getDefault().setSyncEnabled(false);
            SystemProperties.getDefault().setDiscoveryEnabled(false);
        }

        Ethereum ethereum = EthereumFactory.createEthereum();

        if (!SystemProperties.getDefault().blocksLoader().equals(""))
            ethereum.getBlockLoader().loadBlocks();
    }

}

package org.ethereum;

import org.ethereum.cli.CLIInterface;
import org.ethereum.config.SystemProperties;
import org.ethereum.facade.Ethereum;
import org.ethereum.facade.EthereumFactory;
import org.ethereum.mine.Ethash;

import java.io.IOException;
import java.net.URISyntaxException;

/**
 * @author Roman Mandeleil
 * @since 14.11.2014
 */
public class Start {

    public static void main(String args[]) throws IOException, URISyntaxException {
        CLIInterface.call(args);

        final SystemProperties config = SystemProperties.getDefault();
        final boolean actionBlocksLoader = !config.blocksLoader().equals("");
        final boolean actionGenerateDag = config.getConfig().hasPath("ethash.blockNumber");


        if (actionBlocksLoader || actionGenerateDag) {
            config.setSyncEnabled(false);
            config.setDiscoveryEnabled(false);
        }

        Ethereum ethereum = EthereumFactory.createEthereum();

        if (actionBlocksLoader) {
            ethereum.getBlockLoader().loadBlocks();
        } else if (actionGenerateDag) {
            new Ethash(config, config.getConfig().getLong("ethash.blockNumber")).getFullDataset();
            // DAG file has been created, lets exit
            System.exit(0);
        }

    }

}

Add ability to generate DAG file via command line
Add ability to generate DAG file via command line
