HDFS Commands
In my previous blogs, I have already discussed what is HDFS, its features, and architecture. The first step towards the journey to Big Data training is executing HDFS commands & exploring how HDFS works. In this blog, I will talk about the HDFS commands using which you can access the Hadoop File System.
So, let me tell you the important HDFS commands and their working which are used most frequently when working with Hadoop File System.
fsck
HDFS Command to check the health of the Hadoop file system.
Command: hdfs fsck /
ls
HDFS Command to display the list of Files and Directories in HDFS.
Command: hdfs dfs –ls /
mkdir
HDFS Command to create the directory in HDFS.
Usage: hdfs dfs –mkdir /directory_name
Command: hdfs dfs –mkdir /new_edureka
Note: Here we are trying to create a directory named “new_edureka” in HDFS.
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touchz
HDFS Command to create a file in HDFS with file size 0 bytes.
Usage: hdfs dfs –touchz /directory/filename
Command: hdfs dfs –touchz /new_edureka/sample
Note: Here we are trying to create a file named “sample” in the directory “new_edureka” of hdfs with file size 0 bytes.
du
HDFS Command to check the file size.
Usage: hdfs dfs –du –s /directory/filename
Command: hdfs dfs –du –s /new_edureka/sample
cat
HDFS Command that reads a file on HDFS and prints the content of that file to the standard output.
Usage: hdfs dfs –cat /path/to/file_in_hdfs
Command: hdfs dfs –cat /new_edureka/test
text
HDFS Command that takes a source file and outputs the file in text format.
Usage: hdfs dfs –text /directory/filename
Command: hdfs dfs –text /new_edureka/test
copyFromLocal
HDFS Command to copy the file from a Local file system to HDFS.
Usage: hdfs dfs -copyFromLocal <localsrc> <hdfs destination>
Command: hdfs dfs –copyFromLocal /home/edureka/test /new_edureka
Note: Here the test is the file present in the local directory /home/edureka and after the command gets executed the test file will be copied in /new_edureka directory of HDFS.
copyToLocal
HDFS Command to copy the file from HDFS to Local File System.
Usage: hdfs dfs -copyToLocal <hdfs source> <localdst>
Command: hdfs dfs –copyToLocal /new_edureka/test /home/edureka
Note: Here test is a file present in the new_edureka directory of HDFS and after the command gets executed the test file will be copied to local directory /home/edureka
put
HDFS Command to copy single source or multiple sources from local file system to the destination file system.
Usage: hdfs dfs -put <localsrc> <destination>
Command: hdfs dfs –put /home/edureka/test /user
Note: The command copyFromLocal is similar to put command, except that the source is restricted to a local file reference.
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get
HDFS Command to copy files from hdfs to the local file system.
Usage: hdfs dfs -get <src> <localdst>
Command: hdfs dfs –get /user/test /home/edureka
Note: The command copyToLocal is similar to get command, except that the destination is restricted to a local file reference.
count
HDFS Command to count the number of directories, files, and bytes under the paths that match the specified file pattern.
Usage: hdfs dfs -count <path>
Command: hdfs dfs –count /user
rm
HDFS Command to remove the file from HDFS.
Usage: hdfs dfs –rm <path>
Command: hdfs dfs –rm /new_edureka/test
rm -r
HDFS Command to remove the entire directory and all of its content from HDFS.
Usage: hdfs dfs -rm -r <path>
Command: hdfs dfs -rm -r /new_edureka
cp
HDFS Command to copy files from source to destination. This command allows multiple sources as well, in which case the destination must be a directory.
Usage: hdfs dfs -cp <src> <dest>
Command: hdfs dfs -cp /user/hadoop/file1 /user/hadoop/file2
Command: hdfs dfs -cp /user/hadoop/file1 /user/hadoop/file2 /user/hadoop/dir
mv
HDFS Command to move files from source to destination. This command allows multiple sources as well, in which case the destination needs to be a directory.
Usage: hdfs dfs -mv <src> <dest>
Command: hdfs dfs -mv /user/hadoop/file1 /user/hadoop/file2
expunge
HDFS Command that makes the trash empty.
Command: hdfs dfs -expunge
rmdir
HDFS Command to remove the directory.
Usage: hdfs dfs -rmdir <path>
Command: hdfs dfs –rmdir /user/hadoop
usage
HDFS Command that returns the help for an individual command.
Usage: hdfs dfs -usage <command>
Command: hdfs dfs -usage mkdir
Note: By using usage command you can get information about any command.
help
HDFS Command that displays help for given command or all commands if none is specified.
Command: hdfs dfs -help
This is the end of the HDFS Commands blog, I hope it was informative and you were able to execute all the commands. For more HDFS Commands, you may refer Apache Hadoop documentation here.
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