Hadoop cluster - Do I need to replicate my code over all machines before running job?

Question

This is what confuses me, when I use wordcount example, I keep code at master and let him do things with slaves and it runs fine

But when I am running my code, it

Answer 1

With Hadoop Streaming, the code/dependencies have to be copied with the -file flag, if the code is not there on the target machine. Make sure that the map/reduce files and their dependencies are specified in the Hadoop streaming command.

$HADOOP_HOME/bin/hadoop  jar $HADOOP_HOME/hadoop-streaming.jar \
    -input myInputDirs \
    -output myOutputDir \
    -mapper myPythonScript.py \
    -reducer /bin/wc \
    -file myPythonScript.py \
    -file myDictionary.txt \