how to write and execute a hello world program in hadoop?

Am an absolute beginner in apache hadoop. could you please tell me how to do a hello world python program in apache hadoop,and also hoe programs are run in hadoop( I just need to do it in a single culster). I have to do it in no time and am posti开发者_高级运维ng this because am so desperate. I've configured hadoop on my ubuntu 10.10 and some examples programs were run successfully like the

$ bin/hadoop jar hadoop-0.20.1-examples.jar pi 10 100

I have no clue regarding what is happening behind this step.Also kindly tell me a good place to start with hadoop(ebooks,links etc). I should have somehow figured this out if i had time and since i dont have it pls respond and that ll be so helpful.

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i suggest to read docs,

http://hadoop.apache.org/common/docs/r0.20.2/index.html

and the wiki

http://wiki.apache.org/hadoop/FrontPage

in docs, you'll find some samples as shown by answer before. Good luck.

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Since you can run this example in hadoop, it's the same way to run an application. Check the doc here:http://hadoop.apache.org/common/docs/r0.18.2/mapred_tutorial.html And WordCount example is a hello world program for you.

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Look at Yahoo Hadoop Tutorial(http://developer.yahoo.com/hadoop/tutorial/). You may also want to look at the src of the hadoop-examples to get a better feel of the programming with Hadoop. You may also want to readup on Hadoop streaming(http://wiki.apache.org/hadoop/HadoopStreaming)