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.

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.

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.

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)