1. To check all the services are running use
jps
2. Two types of prefix in hadoop command
hdfs dfs (specially with hdfs file system)
hadoop fs (to interact with other file system)
3. To display the list of files/directory present in HDFS filesystem
hadoop fs –ls
hadoop fs –ls <directory>
5. To create directory on HDFS
hadoop fs –mkdir <directory-name>
6. To create a empty file in HDFS
hadoop fs –touchz <file-name>
7. To copy file from LOCAL to HDFS
hadoop fs –copyFromLocal f1.txt <hdfs-path>
hadoop fs –put f1.txt <hdfs-path>
8. To check file content
hadoop fs –cat <hdfs-path>/f1.txt
9. To copy file from HDFS to Local
hadoop fs –copyToLocal <hdfs-path>/f1.txt <local-path>
hadoop fs –get <hdfs-path>/f1.txt <local-path>
10. To copy file from directory to other directory in hdfs
hadoop fs –cp <source> <destination>
11. To move/rename to file within hdfs directory :
hadoop fs –mv <source> <destination>
12. To check disk usage for each file in directory :
hadoop fs –du <source>
13. To test given destination is directory or not:
hadoop fs –test –d <destination>
14. To check is this directory or not – echo$? If answer is 0 then it means it is directory else not
15. To check if destination exist or not in hdfs – hadoop fs –test –e destination
16. To check if destination is file or not – hadoop fs –test –f destination
17. To check given is empty or not – hadoop fs –test –z destination/xyz.txt 18. To move file from local to hdfs – hadoop fs –moveFromLocal a2.txt destination/
19. Merge file in hdfs and copy it into local – hadoop fs –getmerge –nl filename filename ~/Desktop/
20. Append to file in hdfs -- hadoop fs –appendToFile source source destination 21. To check status of hdfs – hadoop fsck - /
22. To check the directory,no. of file in that directory and size – hadoop fs –count directoryname
23. To remove some file – hadoop fs –rm directory/filename
24. Size of file -- Hadoop fs –stat %b directory/filename %r for replication %g for group %u for username %y for last modification
25. Hadoop fs – help any command work like man command in linux
26. Hadoop fs –head directory/filename give first kb of lines
27. Hadoop fs –expunge – to delete the file in trash
28. To change permission to a file – hadoop fs –chmod 777 filename
29. Hadoop fs –setrep –w 3 pathoffile -- to change the replication
30. Hadoop fs –truncate –w 100 filepathname – to reduce the size of lengthy long file
31. To add extra comment to the file – hadoop fs –setfattr –n ‘user.ap’ –v this is dummyfile filepath
32. hadoop fs –getfattr –d filepath – to get attribute
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