Apache Hadoop Getting Started Tutorial Chapter III

Password-free SSH settings

Now verify that you can log in to localhost with ssh without entering your password:

$ ssh localhost
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If you do not enter a password, you cannot log in to localhost with SSH and execute the following command:

$ ssh-keygen-t Rsa-p "-F ~/.ssh/id_rsa
$ cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
$ chmod 0600 ~/.ssh/authorized_keys
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Perform

The following shows a job that runs a MapReduce locally, and here are the steps to run it.

(1) format a new Distributed File system:

$ Bin/hdfs Namenode-format
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(2) Start the NameNode daemon and the DataNode daemon:

$ sbin/start-dfs.sh
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The log of the Hadoop daemon is written to the $HADOOP _log_dir directory ($HADOOP _home/logs by default)

(3) Browse NameNode's network interface, their address defaults to:

namenode-http://localhost:50070/
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(4) Create the HDFS directory to perform the MapReduce job:

$ Bin/hdfs Dfs-mkdir/user
$ Bin/hdfs dfs-mkdir/user/<username>
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(5) Copy the input file to the Distributed File system:

$ Bin/hdfs dfs-put Etc/hadoop input
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(6) Run the sample program provided by the release version:

$ bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.3.jar grep input Output ' dfs[a-z. +
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(7) View output file

Copy the output file from the Distributed file system to the local file system view:

$ bin/hdfs dfs-get Output output
$ cat output/*****
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Alternatively, view the output file on the Distributed File system:

$ Bin/hdfs Dfs-cat output/*
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(8) After completing all the actions, stop the daemon:

$ sbin/stop-dfs.sh
* * You need to learn to continue reading the next chapter. **

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Apache Hadoop Getting Started Tutorial Chapter III