21. Configure, Start, and Validate Apache Mahout

Replace your configuration after upgrading. Copy /etc/mahout/conf from the template to the conf directory in mahout hosts.

To validate Apache Mahout:

Create a test user named "testuser" in the Linux cluster and in HDFS, and log in as that user.
hdfs dfs -put /tmp/sample-test.txt /user/testuser

Export the required environment variables for Mahout:

export JAVA_HOME="your_jdk_home_install_location_here
export HADOOP_HOME=/usr/hdp/current/hadoop-client
export MAHOUT_HOME=/usr/hdp.current/mahout-client
export PATH="$PATH":$HADOOP_HOME/bin:$MAHOUT_HOME/bin
export CLASSPATH="$CLASSPATH":$MAHOUT_HOME

Upload a few megabytes of natural-language plain text to the Linux server as /tmp/sample-test.txt.
Transfer the sample-test.txt file to a subdirectory of the testusers's HDFS home directory.
```
hdfs dfs -mkdir /user/testuser/testdata
hdfs dfs -put /tmp/sample-test.txt /user/testuser/testdata
```
Enter the mahout command to convert the plain text file sample-test.txt into a sequence file stored in the output directory mahouttest:
```
mahout seqdirectory --input /user/testuser/testdata --output /user/testuser/mahouttest -ow --charset utf-8
```

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