org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory hdfs://mycluster/output alread

[hadoop@djtNode1 bin]$ ./hadoop jar ~/app/test/analysis-1.0-SNAPSHOT.jar pv /input/test.txt /output
16/04/30 16:25:09 WARN security.UserGroupInformation: PriviledgedActionException as:hadoop (auth:SIMPLE) cause:org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory hdfs://mycluster/output already exists
org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory hdfs://mycluster/output <strong>already exists</strong>
	at org.apache.hadoop.mapreduce.lib.output.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:146)
	at org.apache.hadoop.mapreduce.JobSubmitter.checkSpecs(JobSubmitter.java:562)
	at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:432)
	at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1306)
	at org.apache.hadoop.mapreduce.Job$10.run(Job.java:1303)
	at java.security.AccessController.doPrivileged(Native Method)
	at javax.security.auth.Subject.doAs(Subject.java:422)
	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1671)
	at org.apache.hadoop.mapreduce.Job.submit(Job.java:1303)
	at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:1324)
	at com.dajiangtai.Pv.main(Pv.java:67)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:71)
	at org.apache.hadoop.util.ProgramDriver.run(ProgramDriver.java:144)
	at com.dajiangtai.MyDriver.main(MyDriver.java:25)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.apache.hadoop.util.RunJar.run(RunJar.java:221)
	at org.apache.hadoop.util.RunJar.main(RunJar.java:136)