cloudera 0.18 -> 0.20

 * hadoop install 
{{{
$ sudo su -
# apt-get install hadoop-0.18 hadoop-0.18-namenode  hadoop-conf-pseudo
# apt-get install hadoop-0.18-datanode hadoop-0.18-jobtracker hadoop-0.18-tasktracker
}}}

 * hadoop namenode format
{{{
# su -s /bin/bash - hadoop -c 'hadoop namenode -format'
}}}
   * use instruction 
{{{
# su -s /bin/bash - hadoop -c " COMMAND "
}}}

 * startup 
{{{
# /etc/init.d/hadoop-namenode start
}}}



 * setup the conf files
....

 * upgrade cloudera-hadoop-0.18 ---> official-hadoop 0.20
{{{
# su -s /bin/bash - hadoop -c " hadoop namenode -upgrade "
}}}