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--- courses:mapreduce-tutorial:step-3 [2012/01/29 23:43]
majlis
+++ courses:mapreduce-tutorial:step-3 [2012/01/31 09:40] (current)
straka Change Perl commandline syntax.
@@ Line 8: / Line 8: @@
 <file perl>
-package Mapper;
+package My::Mapper;
 use Moose;
 with 'Hadoop::Mapper';
@@ Line 18: / Line 18: @@
 }
-package Main;
+package main;
 use Hadoop::Runner;
 my $runner = Hadoop::Runner->new(
-  mapper => Mapper->new(),
+  mapper => My::Mapper->new(),
   input_format => 'TextInputFormat',
   output_format => 'TextOutputFormat',
@@ Line 33: / Line 33: @@
 Resulting script can be executed locally in a single thread using
-  perl script.pl run input_directory output_directory
+  perl script.pl input output_directory
-All files in input_directory are processes. The output_directory must not exist.
+Input can be either file or a directory -- in that case, all files in this directory are processes. The output_directory must not exist.
+=== Standard input and output ===
+Standard input and standard output of the Perl script are used to communicate with the Hadoop framework. Therefore you should use standard error output if you want to print some debugging output using ''print STDERR "Message"''.
 ===== Exercise =====
@@ Line 43: / Line 45: @@
   # NOW EDIT THE FILE
   # $EDITOR step-3-exercise.pl
-  rm -rf step-3-out-ex; perl step-3-exercise.pl run /home/straka/wiki/cs-text-medium/ step-3-out-ex
+  rm -rf step-3-out-ex; perl step-3-exercise.pl /home/straka/wiki/cs-text-medium/ step-3-out-ex
   less step-3-out-ex/part-*
@@ Line 51: / Line 53: @@
   # NOW VIEW THE FILE
   # $EDITOR step-3-solution.pl
-  rm -rf step-3-out-sol; perl step-3-solution.pl run /home/straka/wiki/cs-text-medium/ step-3-out-sol
+  rm -rf step-3-out-sol; perl step-3-solution.pl /home/straka/wiki/cs-text-medium/ step-3-out-sol
   less step-3-out-sol/part-*

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