bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.2.jar grep input output ...报错

20/06/03 16:59:59 INFO client.RMProxy: Connecting to ResourceManager at master/192.168.254.129:8032
org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory hdfs://master:9000/user/basichadoop/output already exists
	at org.apache.hadoop.mapreduce.lib.output.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:146)
	at org.apache.hadoop.mapreduce.JobSubmitter.checkSpecs(JobSubmitter.java:267)
	at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:140)
	at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1297)
	at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1294)
	at java.security.AccessController.doPrivileged(Native Method)
	at javax.security.auth.Subject.doAs(Subject.java:415)
	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1692)
	at org.apache.hadoop.mapreduce.Job.submit(Job.java:1294)
	at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1315)
	at org.apache.hadoop.examples.Grep.run(Grep.java:92)
	at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
	at org.apache.hadoop.examples.Grep.main(Grep.java:101)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:601)
	at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:71)
	at org.apache.hadoop.util.ProgramDriver.run(ProgramDriver.java:144)
	at org.apache.hadoop.examples.ExampleDriver.main(ExampleDriver.java:74)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:601)
	at org.apache.hadoop.util.RunJar.run(RunJar.java:221)
	at org.apache.hadoop.util.RunJar.main(RunJar.java:136)

原因：已有output，但用Linux的ll,ls看不到

解决方法：用hadoop fs

http://hadoop.apache.org/docs/r1.0.4/cn/hdfs_shell.html

问题：无法进入output，无法看到目录里面的文件

解决方法：hadoop fs -get 目录