Tuesday, October 31, 2017

Basic hadoop commands

1. Creating a directory in hdfs

$ hdfs dfs -mkdir <paths>

2. List the directories in hdfs
$ hdfs dfs  -ls  <args>

3. Permissions

4. Putting a file in to hdfs file system
$ hdfs dfs -put <local-src> ... <HDFS_dest_path>

5. Space utilization in hdfs directory
$ hdfs dfs -du URI

6. Downloading files from hdfs to local file system
$ hdfs dfs -get <hdfs_src> <localdst>

7. Merging two files
We can merge two files in hdfs file system into a single file to the local file system as below
$ hdfs dfs -getmerge <src1> <src2> <localdst> [addnl]

8. Copying files or directories recursively
$ hdfs dfs -cp <src-url> <dest-url>

9. Help command
Use help command to access hadoop command manual

10. Seeing the contents of a file
$ hdfs dfs -cat <path[filename]>

11. Copying a file from source to destination in hdfs file system
$ hdfs dfs -cp <source> <dest>

12. Copy a file using copyFromLocal and copyToLocal
$ hdfs dfs -copyFromLocal <localsrc> URI

$ hdfs dfs -copyToLocal [-ignorecrc] [-crc] URI <localdst>

13. Move file from source to destination in hdfs file system
$ hdfs dfs -mv <src> <dest>

14. Remove a file or directory from hdfs file system
$ hdfs dfs -rm <arg>

15. Remove files recursively

16. To display last few lines of a file
$ hdfs dfs -tail <path[filename]>

17. Hadoop version

18. To check amount of space used by hdfs file system

19. To count the number of files and directories in hdfs


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