Daniel, You can find those std out statements in  "{LOG
Directory}/userlogs/{task attemp id}/stdout" file.

Same way you can find std err statements in "{LOG Directory}/userlogs/{task
attemp id}/stderr" and log statements in "{LOG Directory}/userlogs/{task
attemp id}/syslog".

Devaraj K 

-----Original Message-----
From: Daniel,Wu [mailto:hadoop...@163.com] 
Sent: Thursday, July 28, 2011 11:47 AM
To: common-user@hadoop.apache.org
Subject: where to find the log info

Hi everyone,

I am new to it, and want to do some debug/log. I'd like to check what the
value is for each mapper execution. If I add the following code in bold,
where can I find the log info? If I can't do it in this way, how should I
do?

     public void map(Object key, Text value, Context context
                    ) throws IOException, InterruptedException {
      StringTokenizer itr = new StringTokenizer(value.toString());
      System.out.println(value.toString);
      while (itr.hasMoreTokens()) {
        word.set(itr.nextToken());
        context.write(word, one);
      }
    }
  }

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