From Michael Noll’s hadoop on ubuntu post

mkdir /var/lib/hadoop
chown mmm.mmm /var/lib/hadoop

hadoop datanode -format

bin/start-all.sh 

hadoop dfs -copyFromLocal /tmp/gutenberg gutenberg

hadoop dfs -ls

hadoop jar /usr/local/hadoop/hadoop-mapred-examples-0.21.0.jar wordcount gutenberg gutenberg-output

hadoop dfs -ls
hadoop dfs -ls gutenberg-output

bin/hadoop dfs -cat gutenberg-output/part-r-00000
mkdir /tmp/gutenberg-output
bin/hadoop dfs -getmerge gutenberg-output /tmp/gutenberg-output
head /tmp/gutenberg-output/gutenberg-output