001/** 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018package org.apache.hadoop.util; 019 020import java.io.IOException; 021import java.io.PrintStream; 022 023import org.apache.hadoop.classification.InterfaceAudience; 024import org.apache.hadoop.classification.InterfaceStability; 025import org.apache.hadoop.conf.Configuration; 026 027/** 028 * A utility to help run {@link Tool}s. 029 * 030 * <p><code>ToolRunner</code> can be used to run classes implementing 031 * <code>Tool</code> interface. It works in conjunction with 032 * {@link GenericOptionsParser} to parse the 033 * <a href="{@docRoot}/../hadoop-project-dist/hadoop-common/CommandsManual.html#Generic_Options"> 034 * generic hadoop command line arguments</a> and modifies the 035 * <code>Configuration</code> of the <code>Tool</code>. The 036 * application-specific options are passed along without being modified. 037 * </p> 038 * 039 * @see Tool 040 * @see GenericOptionsParser 041 */ 042@InterfaceAudience.Public 043@InterfaceStability.Stable 044public class ToolRunner { 045 046 /** 047 * Runs the given <code>Tool</code> by {@link Tool#run(String[])}, after 048 * parsing with the given generic arguments. Uses the given 049 * <code>Configuration</code>, or builds one if null. 050 * 051 * Sets the <code>Tool</code>'s configuration with the possibly modified 052 * version of the <code>conf</code>. 053 * 054 * @param conf <code>Configuration</code> for the <code>Tool</code>. 055 * @param tool <code>Tool</code> to run. 056 * @param args command-line arguments to the tool. 057 * @return exit code of the {@link Tool#run(String[])} method. 058 */ 059 public static int run(Configuration conf, Tool tool, String[] args) 060 throws Exception{ 061 if(conf == null) { 062 conf = new Configuration(); 063 } 064 GenericOptionsParser parser = new GenericOptionsParser(conf, args); 065 //set the configuration back, so that Tool can configure itself 066 tool.setConf(conf); 067 068 //get the args w/o generic hadoop args 069 String[] toolArgs = parser.getRemainingArgs(); 070 return tool.run(toolArgs); 071 } 072 073 /** 074 * Runs the <code>Tool</code> with its <code>Configuration</code>. 075 * 076 * Equivalent to <code>run(tool.getConf(), tool, args)</code>. 077 * 078 * @param tool <code>Tool</code> to run. 079 * @param args command-line arguments to the tool. 080 * @return exit code of the {@link Tool#run(String[])} method. 081 */ 082 public static int run(Tool tool, String[] args) 083 throws Exception{ 084 return run(tool.getConf(), tool, args); 085 } 086 087 /** 088 * Prints generic command-line argurments and usage information. 089 * 090 * @param out stream to write usage information to. 091 */ 092 public static void printGenericCommandUsage(PrintStream out) { 093 GenericOptionsParser.printGenericCommandUsage(out); 094 } 095 096 097 /** 098 * Print out a prompt to the user, and return true if the user 099 * responds with "y" or "yes". (case insensitive) 100 */ 101 public static boolean confirmPrompt(String prompt) throws IOException { 102 while (true) { 103 System.err.print(prompt + " (Y or N) "); 104 StringBuilder responseBuilder = new StringBuilder(); 105 while (true) { 106 int c = System.in.read(); 107 if (c == -1 || c == '\r' || c == '\n') { 108 break; 109 } 110 responseBuilder.append((char)c); 111 } 112 113 String response = responseBuilder.toString(); 114 if (response.equalsIgnoreCase("y") || 115 response.equalsIgnoreCase("yes")) { 116 return true; 117 } else if (response.equalsIgnoreCase("n") || 118 response.equalsIgnoreCase("no")) { 119 return false; 120 } 121 System.err.println("Invalid input: " + response); 122 // else ask them again 123 } 124 } 125}