Hadoop Basic Commands

• List all hadoop filesystem shell commands :

$> hadoop fs

• Help for the hadoop filesystem command :

$> hadoop fs -help

• Print the version of Hadoop :

$> hadoop version

• Print the content of the root directory (HDFS) :

$> hadoop fs -ls /

• Print the amount of space used :

$> hadoop fs -df hdfs:/

• Count the number of directory, files and bytes :

$> hadoop fs -count hdfs:/

• Create a new directory "Subdirectory" under root :

$> hadoop fs -mkdir Root/Directory/Subdirectory

• Upload a file A.TXT from local pathtofile to hdfs "Subdirectory" :

$> hadoop fs -put pathtofile/A.TXT /Root/Directory/Subdirectory

• Print / show the contents of the "Subdirectory" :

$> hadoop fs -ls Root/Directory/Subdirectory

• Delete / Remove the file A.TXT from the hdfs :

$> hadoop fs -rm Root/Directory/Subdirectory/A.TXT

• Delete / clear / purge all files in the trash bin :

$> hadoop fs -expunge

• Command to copy a file from local to Hadoop (Alternative to put command) :

$> hadoop fs -copyFromLocal pathtofile/A.TXT /Root/Directory/Subdirectory

• Command to view the contents of a file on HDFS :

$> hadoop fs -cat pathtofile/A.TXT

• Command to copy a file from Hadoop FS to Local (Alternative to get command) :

$> hadoop fs -copyToLocal /Root/Directory/Subdirectory /pathtolocal/A.TXT 

• Copying files between 2 HDFS directories :

$> hadoop fs -cp /path/to/hadoop1/*.txt /path/to/hadoop2/

• Download file A.TXT from HDFS to local path :

$> hadoop fs -get hadoop/A.txt /path/to/local

• Unix Tail command on hadoop fs (HDFS)n:

$> hadoop fs -tail path/to/hadoop/A.TXT

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