Hadoop FS Shell test

Introduction

In this lab, we will immerse ourselves in a thrilling scenario set in an abandoned sanatorium. You will step into the shoes of an intrepid explorer navigating the ruins of this eerie location. Your objective is to utilize the Hadoop FS Shell test commands to uncover hidden data within the Hadoop Distributed File System (HDFS).

Skills Graph

Exploring the Abandoned Sanatorium

In this step, you will begin your exploration by executing Hadoop FS Shell test commands to locate and validate specific files within the HDFS.

1. Use the following command to verify if a file exists in the HDFS:

hadoop fs -test -e /data/secret_file.txt

2. Explain the purpose of the command and interpret the output.

The meaning of this command is to test whether the specified path exists in Hadoop Distributed File System (HDFS).

Specifically, the meaning of each part of this command is as follows:

• hadoop fs: This is the prefix of the Hadoop filesystem command that is used to interact with the Hadoop Distributed File System.
• -test: This is an option indicating that a test operation is to be performed.
• -e: This is also an option that indicates to check if the specified path exists.
• /data/secret_file.txt: This is the path to be tested, i.e. /data/secret_file.txt.

So, the purpose of this command is to test if the /data/secret_file.txt file exists in HDFS.

hadoop fs -test -e /data/secret_file.txt
echo $?

View the output of the above command.

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Uncovering Data Clues

In this step, you will continue your expedition within the sanatorium and employ more Hadoop FS Shell test commands to unravel additional data clues stored in the HDFS.

1. Validate the reading ownership of a directory using:

hadoop fs -test -r /data/top_secret

2. Analyze the results and explain their significance.

The meaning of this command is to test whether the specified path exists and has owner reading permissions in Hadoop Distributed File System (HDFS).

Specifically, the meaning of each part of this command is as follows:

• hadoop fs: This is the prefix of the Hadoop filesystem command used to interact with the Hadoop Distributed File System.
• -test: This is an option indicating that a test operation is to be performed.
• -r: This is also an option that indicates to check the reading permissions of the specified path.
• /data/top_secret: This is the path to be tested, i.e. /data/top_secret.

Thus, the purpose of this command is to test whether the /data/top_secret path exists in HDFS and whether the current user has owner reading permissions for that path.

hadoop fs -test -e /data/secret_file.txt
echo $?

View the output of the above command.

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Summary

In this lab, the macabre setting of an abandoned sanatorium serves as the backdrop for mastering Hadoop FS Shell test commands. By following the outlined steps, students can acquire hands-on experience in navigating HDFS and validating file presence, ownership, and permissions. Through this immersive approach, learners can enhance their understanding of Hadoop's file system operations while delving into a compelling narrative-driven learning environment.