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Apache Hadoop MapReduce Streaming
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.streaming;
import java.util.Arrays;
import org.apache.hadoop.util.ToolRunner;
/** The main entry point. Usually invoked with the script
* bin/hadoop jar hadoop-streaming.jar args.
*/
public class HadoopStreaming {
public static void main(String[] args) throws Exception {
if (args.length < 1) {
System.err.println("No Arguments Given!");
printUsage();
System.exit(1);
}
int returnStatus = 0;
String cmd = args[0];
String[] remainingArgs = Arrays.copyOfRange(args, 1, args.length);
if (cmd.equalsIgnoreCase("dumptb")) {
DumpTypedBytes dumptb = new DumpTypedBytes();
returnStatus = ToolRunner.run(dumptb, remainingArgs);
} else if (cmd.equalsIgnoreCase("loadtb")) {
LoadTypedBytes loadtb = new LoadTypedBytes();
returnStatus = ToolRunner.run(loadtb, remainingArgs);
} else if (cmd.equalsIgnoreCase("streamjob")) {
StreamJob job = new StreamJob();
returnStatus = ToolRunner.run(job, remainingArgs);
} else { // for backward compatibility
StreamJob job = new StreamJob();
returnStatus = ToolRunner.run(job, args);
}
if (returnStatus != 0) {
System.err.println("Streaming Command Failed!");
System.exit(returnStatus);
}
}
private static void printUsage() {
System.out.println("Usage: mapred streaming [options]");
System.out.println("Options:");
System.out.println(" dumptb Dumps all files that match the"
+ " given pattern to ");
System.out.println(" standard output as typed " +
"bytes.");
System.out.println(" loadtb Reads typed bytes from standard input" +
" and stores them in");
System.out.println(" a sequence file in the specified path");
System.out.println(" [streamjob] Runs streaming job with given" +
" arguments");
}
}