Exploring HDFS commands

To perform filesystem related tasks, the commands begin with hdfs dfs. The filesystem commands have been designed to behave similarly to the corresponding Unix/Linux filesystem commands.

What is a URI? URI stands for Uniform Resource Identifier. In the commands that are listed as follows, you will observe the use of URI for file locations. The URI syntax to access a file in HDFS is hdfs://namenodehost/parent/child/<file>.

Commonly used HDFS commands

The following are some of the most commonly used HDFS commands:

• ls: This command lists files in HDFS.

  The syntax of the ls command is hdfs dfs -ls <args>. The following is the screenshot showing an example of the ls command:

  
• cat: This command displays the contents of file/files in the terminal.

  The syntax of the cat command is hdfs dfs -cat URI [URI …]. The following is a sample output of the cat command:

  
• copyFromLocal: This command copies a file/files from the local filesystem to HDFS.

  The syntax of the copyFromLocal...