HDFS Filesystem Operations

Few basic Hadoop HDFS operations managed by shell commands given by command line interface are

• Create a directory in HDFS at given path(s).

Usage: hadoop fs -mkdir <paths>

Example: hadoop fs -mkdir /user/saurzcode/dir1 /user/saurzcode/dir2

• List the contents of a directory.

Usage : hadoop fs -ls <args>

Example: hadoop fs -ls /user/saurzcode

• Upload and download a file in HDFS.

Upload: hadoop fs -put:

Copy single src file, or multiple src files from local file system to the Hadoop data file system

Usage: hadoop fs -put <localsrc> … <HDFS_dest_Path>

Example: hadoop fs -put /home/saurzcode/Samplefile.txt /user/saurzcode/dir3/

Download:

hadoop fs -get:

• Copies/Downloads files to the local file system

Usage: hadoop fs -get <hdfs_src> <localdst>

Example: hadoop fs -get /user/saurzcode/dir3/Samplefile.txt /home/

• See contents of a file

Same as unix cat command:

Usage: hadoop fs -cat <path[filename]>

Example: hadoop fs -cat /user/saurzcode/dir1/abc.txt

• Copy a file from source to destination

This command allows multiple sources as well in which case the destination must be a directory.

Usage: hadoop fs -cp <source> <dest>

Example: hadoop fs -cp /user/saurzcode/dir1/abc.txt /user/saurzcode/dir2

• Copy a file from/To Local file system to HDFS

copyFromLocal

Usage: hadoop fs -copyFromLocal <localsrc> URI

Example: hadoop fs -copyFromLocal /home/saurzcode/abc.txt /user/saurzcode/abc.txt

Similar to put command, except that the source is restricted to a local file reference.

copyToLocal

Usage: hadoop fs -copyToLocal [-ignorecrc] [-crc] URI <localdst>

Similar to get command, except that the destination is restricted to a local file reference.

• Move file from source to destination.

Moving files across filesystem is not permitted.

Usage : hadoop fs -mv <src> <dest>

Example: hadoop fs -mv /user/saurzcode/dir1/abc.txt /user/saurzcode/dir2

• Remove a file or directory in HDFS.

Remove files specified as argument. Deletes directory only when it is empty

Usage : hadoop fs -rm <arg>

Example: hadoop fs -rm /user/saurzcode/dir1/abc.txt

• Recursive version of delete.

Usage : hadoop fs -rmr <arg>

Example: hadoop fs -rmr /user/saurzcode/

• Display last few lines of a file.

Similar to tail command in Unix.

Usage : hadoop fs -tail <path[filename]>

Example: hadoop fs -tail /user/saurzcode/dir1/abc.txt

• Display the aggregate length of a file.

Usage : hadoop fs -du <path>

Example: hadoop fs -du /user/saurzcode/dir1/abc.txt