Hadoop - Command Reference


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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.

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.



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