2、Input path does not exist异常
（1）异常描述
当你在当前Hadoop目录下面创建一个input目录，并cp某些文件到里面，开始执行：
[root@localhost hadoop-0.19.0]# bin/hadoop namenode -format
[root@localhost hadoop-0.19.0]# bin/start-all.sh
这时候，你认为input已经存在，应该可以执行wordcount任务了：
[root@localhost hadoop-0.19.0]# bin/hadoop jar hadoop-0.19.0-examples.jar wordcount input output
结果抛出一堆异常，信息如下：
org.apache.hadoop.mapred.InvalidInputException: Input path does not exist: hdfs://localhost:9000/user/root/input
at org.apache.hadoop.mapred.FileInputFormat.listStatus(FileInputFormat.java:179)
at org.apache.hadoop.mapred.FileInputFormat.getSplits(FileInputFormat.java:190)
at org.apache.hadoop.mapred.JobClient.submitJob(JobClient.java:782)
at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1127)
at org.apache.hadoop.examples.WordCount.run(WordCount.java:149)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
at org.apache.hadoop.examples.WordCount.main(WordCount.java:155)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:68)
at org.apache.hadoop.util.ProgramDriver.driver(ProgramDriver.java:141)
at org.apache.hadoop.examples.ExampleDriver.main(ExampleDriver.java:61)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.util.RunJar.main(RunJar.java:165)
at org.apache.hadoop.mapred.JobShell.run(JobShell.java:54)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79)
at org.apache.hadoop.mapred.JobShell.main(JobShell.java:68)
上述异常，我模拟的过程是：
[root@localhost hadoop-0.19.0]# bin/hadoop fs -rmr input
Deleted hdfs://localhost:9000/user/root/input
[root@localhost hadoop-0.19.0]# bin/hadoop fs -rmr output
Deleted hdfs://localhost:9000/user/root/output
因为之前我已经成功执行过一次。
（2）异常分析
应该不用多说了，是因为本地的input目录并没有上传到HDFS上，所出现org.apache.hadoop.mapred.InvalidInputException: Input path does not exist: hdfs://localhost:9000/user/root/input
在我的印象中，好像使用hadoop-0.16.4的时候，只要input目录存在，是不用执行上传命令，就可以运行的，后期的版本是不行的。
只需要执行上传的命令即可：
[root@localhost hadoop-0.19.0]# bin/hadoop fs -put input/ input