Installing Hadoop on ubuntu 12.04

Its a simple procedure

1. Download the latest stable version from apache hadoop or from one of its mirror sites
2. Extract/Untar the content to a newly created folder named hadoop on local file-system.
3. Make sure you've already setup your environment variable for JAVA_HOME.
4. Create env. var. for HADOOP_INSTALL and point it to hadoop-directory.
5. Include the bin directory in PATH.
6. For the new version(2.0 based) include the sbin directory too in PATH.
7. If everything is successful from above install, to test..

Type in..

$hadoop version

If the following is displayed means hadoop is installed on your local machine

Hadoop 0.23.6
Subversion https://svn.apache.org/repos/asf/hadoop/common
   /branches/branch-0.23.6/hadoop-common-project
   /hadoop-common -r 1439589
Compiled by tgraves on Tue Jan 29 03:52:15 UTC 2013
From source with checksum ba089c8e3aa974e8ef5b8f6ada0f4c04

P.S - To add environment var in ubuntu, most easy would be to add it in .bashrc file which is present in HOME
- Open it with - "

$ gedit .bashrc
add following environment variable to it..
#Home where java is installed
export JAVA_HOME="/path/to/OpenJDK"
#Home where hadoop is placed
export HADOOP_INSTALL="/path/to/hadoop"
#Adding homes to path
add export PATH=${PATH}:/path/to/your/hadoop/folder/bin