我已经安装了hadoop2.7.1稳定版。我按照tom white的书以伪分布式模式安装。我设置了所有的环境变量，比如java\u home、hadoop\u home、path等等。。我配置了yarn-site.xml、hdfs-site.xml、core-site.xml、mapred-site.xml。
我使用以下命令复制了示例文件file.txt。

$hadoop fs -copyFromLocal textFiles/file.txt file.txt

这让我明白

Found 2 items
-rw-r--r--   1 RAMA supergroup       3737 2015-12-27 21:52 file.txt
drwxr-xr-x   - RAMA supergroup          0 2015-12-27 22:17 input

当我在hadoop-mapreduce-examples-2.7.1.jar中使用以下命令执行wordcount程序时

RAMAs-MacBook-Pro:hadoop-2.7.1 RAMA$ hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.1.jar wordcount file.txt output

它给了我以下的例外，我无法找到任何可行的解决办法。

15/12/27 22:41:52 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
15/12/27 22:41:53 INFO client.RMProxy: Connecting to ResourceManager at localhost/127.0.0.1:8032
15/12/27 22:41:53 INFO input.FileInputFormat: Total input paths to process : 1
15/12/27 22:41:53 INFO mapreduce.JobSubmitter: number of splits:1
15/12/27 22:41:53 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1451216397139_0020
15/12/27 22:41:54 INFO impl.YarnClientImpl: Submitted application application_1451216397139_0020
15/12/27 22:41:54 INFO mapreduce.Job: The url to track the job: http://192.168.1.6:8088/proxy/application_1451216397139_0020/
15/12/27 22:41:54 INFO mapreduce.Job: Running job: job_1451216397139_0020
15/12/27 22:41:57 INFO mapreduce.Job: Job job_1451216397139_0020 running in uber mode : false
15/12/27 22:41:57 INFO mapreduce.Job:  map 0% reduce 0%
15/12/27 22:41:57 INFO mapreduce.Job: Job job_1451216397139_0020 failed with state FAILED due to: Application application_1451216397139_0020 failed 2 times due to AM Container for appattempt_1451216397139_0020_000002 exited with  exitCode: 127
For more detailed output, check application tracking page:http://192.168.1.6:8088/cluster/app/application_1451216397139_0020Then, click on links to logs of each attempt.
Diagnostics: Exception from container-launch.
Container id: container_1451216397139_0020_02_000001
Exit code: 127
Stack trace: ExitCodeException exitCode=127: 
at org.apache.hadoop.util.Shell.runCommand(Shell.java:545)
at org.apache.hadoop.util.Shell.run(Shell.java:456)
at org.apache.hadoop.util.Shell$ShellCommandExecutor.execute(Shell.java:722)
at org.apache.hadoop.yarn.server.nodemanager.DefaultContainerExecutor.launchContainer(DefaultContainerExecutor.java:211)
at org.apache.hadoop.yarn.server.nodemanager.containermanager.launcher.ContainerLaunch.call(ContainerLaunch.java:302)
at org.apache.hadoop.yarn.server.nodemanager.containermanager.launcher.ContainerLaunch.call(ContainerLaunch.java:82)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)

Container exited with a non-zero exit code 127
Failing this attempt. Failing the application.
15/12/27 22:41:57 INFO mapreduce.Job: Counters: 0

任何建议/意见都很有帮助。。。