hadoop basic command-programmingraja

Version command

It will Prints the version.

syntax:  C:\Users\HP>Hadoop version

mkdir and ls command

Mkdir command is used to create a directory. In Hadoop dfs there is no home directory by default. 

Syntax:  hdfs dfs -mkdir /<folder name>

e.g:

C:\hadoop-2.8.0>hdfs dfs -mkdir /programmingraja

Ls command is used to list all the files.It will print all the directories present in HDFS.

Syntax: C:\hadoop-2.8.0>hdfs dfs -ls /

df command

df command is used for showing the capacity,size and free space available on the hdfs file system.The - h option formats the file size in human readable form.

Syntax:  C:\hadoop-2.8.0>Hdfc dfs -df

               C:\hadoop-2.8.0>Hdfc dfs -df -h

touchz command

 Touchz command is used to creates an empty file.

In below example we created raja.txt file in programmingraja directory. 

Syntax:        hdfsdfs  -touchz<file_path>

E.g.

C:\hadoop-2.8.0>hdfs dfs -touchz  /programmingraja/raja.txt

lsr command

lsr command is used to show all files in directory.

Syntax: C:\hadoop-2.8.0>hdfs dfs -lsr /

put command

put command is used to copy files or folders from local file system to hdfs store. put command is the most important command. 

For example I want to copy pro2.txt file which is present in my computer location --> c:/hadoop_pro to HDFS store so for that put command is used.

Syntax:   

 hdfsdfs -copyFromLocal<local file path><dest(present on hdfs)>

E.g.

C:\hadoop-2.8.0>hdfs dfs -put ../hadoop_pro/pro2.txt /programmingraja

get command

get command is used to copy files or folders from hdfs store to local file system(my computer).
Here I have a raja.txt file in HDFS store now by using get commandwe get copy of this file to our local file system location--> c:\hadoop_pro 

Syntax:

hdfsdfs -copyToLocal<<srcfile(on hdfs)><local file dest>

E.g.

C:\hadoop-2.8.0>hdfs dfs -get /programmingraja/raja.txt  ../hadoop_pro

cat command

Cat command is used to print file contents.

Syntax: hdfsdfs -cat <path>

E.g.

C:\hadoop-2.8.0>hdfs dfs -cat /programmingraja/pro2.txt

cp command

cp command is used to copy files within hdfs. 

Here,we have two folders programmingraja and ekta now we copy programmingraja folder to ekta.

Syntax: hdfsdfs -cp  <src(on hdfs)><dest(on hdfs)>

E.g.

C:\hadoop-2.8.0>dfs -cp /programmingraja  /ekta

du command

It will give the size of each file in directory.

Syntax:   hdfsdfs -du  <dirName>

E.g.

C:\hadoop-2.8.0>hdfs dfs -du /programmingraja

dus command

It will give the total size of directory.

Syntax:  hdfsdfs -dus<dirName>

E.g.

C:\hadoop-2.8.0>hdfs dfs -dus /ekta

mv command

This command is used to move files within hdfs. 

Syntax: hdfsdfs -mv  <src(on hdfs)><src(on hdfs)>

here we have two directory ekta and programmingraja.

lets cut abc.txt file from ekta to programmingraja.

After successful execution of mv command abc.txt file is moved from ekta to programmingraja.

rmr command

This command removes entire directory from HDFS store. 

Syntax: hdfs dfs -rmr<filename/directoryName>

E.g.

C:\hadoop-2.8.0>hdfs dfs -rmr /mypro

checksum command

E.g.

C:\hadoop-2.8.0>hdfs dfs -checksum /ekta/pro2.txt

count command

count command is used to count number of files,directories and bytes.

Syntax:

C:\hadoop-2.8.0>hdfs dfs -count -v /

C:\hadoop-2.8.0>hdfs dfs -count -v -q /

C:\hadoop-2.8.0>hdfs dfs -count -v -u/

fsck command

The fsck Hadoop command is used to check health of the HDFS.

E.g.

C:\hadoop-2.8.0>hdfs fsck /programmingraja/ -files