Hadoop - Command Reference


Advertisements

There are many more commands in "$HADOOP_HOME/bin/hadoop fs" than are demonstrated here, although these basic operations will get you started. Running ./bin/hadoop dfs with no additional arguments will list all the commands that can be run with the FsShell system. Furthermore, $HADOOP_HOME/bin/hadoop fs -help commandName will display a short usage summary for the operation in question, if you are stuck.

A table of all the operations is shown below. The following conventions are used for parameters −

"<path>" means any file or directory name. 
"<path>..." means one or more file or directory names. 
"<file>" means any filename. 
"<src>" and "<dest>" are path names in a directed operation. 
"<localSrc>" and "<localDest>" are paths as above, but on the local file system. 

All other files and path names refer to the objects inside HDFS.

Sr.No Command & Description
1

-ls <path>

Lists the contents of the directory specified by path, showing the names, permissions, owner, size and modification date for each entry.

2

-lsr <path>

Behaves like -ls, but recursively displays entries in all subdirectories of path.

3

-du <path>

Shows disk usage, in bytes, for all the files which match path; filenames are reported with the full HDFS protocol prefix.

4

-dus <path>

Like -du, but prints a summary of disk usage of all files/directories in the path.

5

-mv <src><dest>

Moves the file or directory indicated by src to dest, within HDFS.

6

-cp <src> <dest>

Copies the file or directory identified by src to dest, within HDFS.

7

-rm <path>

Removes the file or empty directory identified by path.

8

-rmr <path>

Removes the file or directory identified by path. Recursively deletes any child entries (i.e., files or subdirectories of path).

9

-put <localSrc> <dest>

Copies the file or directory from the local file system identified by localSrc to dest within the DFS.

10

-copyFromLocal <localSrc> <dest>

Identical to -put

11

-moveFromLocal <localSrc> <dest>

Copies the file or directory from the local file system identified by localSrc to dest within HDFS, and then deletes the local copy on success.

12

-get [-crc] <src> <localDest>

Copies the file or directory in HDFS identified by src to the local file system path identified by localDest.

13

-getmerge <src> <localDest>

Retrieves all files that match the path src in HDFS, and copies them to a single, merged file in the local file system identified by localDest.

14

-cat <filen-ame>

Displays the contents of filename on stdout.

15

-copyToLocal <src> <localDest>

Identical to -get

16

-moveToLocal <src> <localDest>

Works like -get, but deletes the HDFS copy on success.

17

-mkdir <path>

Creates a directory named path in HDFS.

Creates any parent directories in path that are missing (e.g., mkdir -p in Linux).

18

-setrep [-R] [-w] rep <path>

Sets the target replication factor for files identified by path to rep. (The actual replication factor will move toward the target over time)

19

-touchz <path>

Creates a file at path containing the current time as a timestamp. Fails if a file already exists at path, unless the file is already size 0.

20

-test -[ezd] <path>

Returns 1 if path exists; has zero length; or is a directory or 0 otherwise.

21

-stat [format] <path>

Prints information about path. Format is a string which accepts file size in blocks (%b), filename (%n), block size (%o), replication (%r), and modification date (%y, %Y).

22

-tail [-f] <file2name>

Shows the last 1KB of file on stdout.

23

-chmod [-R] mode,mode,... <path>...

Changes the file permissions associated with one or more objects identified by path.... Performs changes recursively with R. mode is a 3-digit octal mode, or {augo}+/-{rwxX}. Assumes if no scope is specified and does not apply an umask.

24

-chown [-R] [owner][:[group]] <path>...

Sets the owning user and/or group for files or directories identified by path.... Sets owner recursively if -R is specified.

25

-chgrp [-R] group <path>...

Sets the owning group for files or directories identified by path.... Sets group recursively if -R is specified.

26

-help <cmd-name>

Returns usage information for one of the commands listed above. You must omit the leading '-' character in cmd.

Useful Video Courses


Video

Hadoop Administration Online Training

39 Lectures 2.5 hours

Arnab Chakraborty

Video

Big Data & Hadoop Online Training

65 Lectures 6 hours

Arnab Chakraborty

Video

Learn Hadoop and Spark analytics

12 Lectures 1 hours

Pranjal Srivastava

Video

Real Time Spark Project for Beginners: Hadoop, Spark, Docker

24 Lectures 6.5 hours

Pari Margu

Video

Big Data Hadoop

89 Lectures 11.5 hours

TELCOMA Global

Video

Learn Big Data Hadoop: Hands-On for Beginner

43 Lectures 1.5 hours

Bigdata Engineer

Advertisements