3、 通过WEB查看hadoop
运行hadoop的example-wordcount
Wordcount程序是一个简单的计算输入文件中每个单词出现的次数，并输出到指定的目录下。该程序是官方的例子，在hadoop-0.21.0安装目录下的：hadoop-mapred-examples-0.21.0.jar
在hdfs上建立程序的输入目录和文件，同时建立程序的输出目录.
[hadoop@hadoop00~]$ mkdir input
[hadoop@hadoop00 ~]$ cat a a a a a b b b c c c c cc c c c 1 1 1 > input/file
[hadoop@hadoop00 ~]$ hadoop fs–mkdir /wordcount
[hadoop@hadoop00 ~]$ hadoop fs –put input/wordcount
[hadoop@hadoop00~]$ hadoop jar hadoop-0.21.0/hadoop-mapred-examples-0.21.0.jarwordcount /wordcount/input /wordcount/output
11/09/24 08:11:25INFO security.Groups: Group mappingimpl=org.apache.hadoop.security.ShellBasedUnixGroupsMapping;cacheTimeout=300000
11/09/24 08:11:26 WARN conf.Configuration:mapred.task.id is deprecated. Instead, usemapreduce.task.attempt.id
11/09/24 08:11:26 WARNmapreduce.JobSubmitter: Use GenericOptionsParser for parsing thearguments. Applications should implement Tool for the same.
11/09/2408:11:26 INFO input.FileInputFormat: Total input paths to process :2
11/09/24 08:11:26 WARN conf.Configuration: mapred.map.tasks isdeprecated. Instead, use mapreduce.job.maps
11/09/24 08:11:26 INFOmapreduce.JobSubmitter: number of splits:2
11/09/24 08:11:27 INFOmapreduce.JobSubmitter: adding the following namenodes' delegationtokens:null
11/09/24 08:11:28 INFO mapreduce.Job: map 0% reduce 0%
11/09/24 08:11:44 INFO mapreduce.Job: map50% reduce 0%
11/09/24 08:11:50 INFO mapreduce.Job: map 100%reduce 0%
11/09/24 08:11:57 INFO mapreduce.Job: map 100%reduce 100%
11/09/24 08:11:59 INFO mapreduce.Job: Job complete:job_201109240745_0002
11/09/24 08:11:59 INFO mapreduce.Job:Counters: 34
……
[hadoop@hadoop00~]$ hadoop fs -cat /wordcount/output/part-r-00000
11/09/2408:18:09 INFO security.Groups: Group mappingimpl=org.apache.hadoop.security.ShellBasedUnixGroupsMapping;cacheTimeout=300000
11/09/24 08:18:09 WARN conf.Configuration:mapred.task.id is deprecated. Instead, usemapreduce.task.attempt.id
1 3
a 5
b 3
c 9