hdfs_shell

HDFS File System Shell Guide Table of contents 1 Overview............................................................................................................................3 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 cat ................................................................................................................................. 3 chgrp ............................................................................................................................. 3 chmod ........................................................................................................................... 3 chown ........................................................................................................................... 4 copyFromLocal..............................................................................................................4 copyToLocal..................................................................................................................4 count ............................................................................................................................. 4 cp .................................................................................................................................. 4 du................................................................................................................................... 5 dus ...............................................................................................................................5 expunge .......................................................................................................................5 get ................................................................................................................................5 getmerge ......................................................................................................................6 ls...................................................................................................................................6 lsr................................................................................................................................. 6 mkdir ...........................................................................................................................7 moveFromLocal ..........................................................................................................7 moveToLocal............................................................................................................... 7 mv ............................................................................................................................... 7 put ............................................................................................................................... 8 rm ................................................................................................................................ 8 rmr ...............................................................................................................................8 setrep ...........................................................................................................................9 Copyright © 2008 The Apache Software Foundation. All rights reserved. 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 HDFS File System Shell Guide 1.24 1.25 1.26 1.27 1.28 stat ...............................................................................................................................9 tail ............................................................................................................................... 9 test .............................................................................................................................10 text ............................................................................................................................ 10 touchz ........................................................................................................................10 Page 2 Copyright © 2008 The Apache Software Foundation. All rights reserved. HDFS File System Shell Guide

1. Overview The FileSystem (FS) shell is invoked by bin/hadoop fs . All FS shell commands take path URIs as arguments. The URI format is scheme://autority/path. For HDFS the scheme is hdfs, and for the local filesystem the scheme is file. The scheme and authority are optional. If not specified, the default scheme specified in the configuration is used. An HDFS file or directory such as /parent/child can be specified as hdfs://namenodehost/parent/child or simply as /parent/child (given that your configuration is set to point to hdfs://namenodehost). Most of the commands in FS shell behave like corresponding Unix commands. Differences are described with each of the commands. Error information is sent to stderr and the output is sent to stdout. 1.1. cat Usage: hadoop fs -cat URI [URI …] Copies source paths to stdout. Example: • hadoop fs -cat hdfs://nn1.example.com/file1 hdfs://nn2.example.com/file2 • hadoop fs -cat file:///file3 /user/hadoop/file4 Exit Code: Returns 0 on success and -1 on error. 1.2. chgrp Usage: hadoop fs -chgrp [-R] GROUP URI [URI …] Change group association of files. With -R, make the change recursively through the directory structure. The user must be the owner of files, or else a super-user. Additional information is in the HDFS Admin Guide: Permissions. 1.3. chmod Usage: hadoop fs -chmod [-R] URI [URI …] Change the permissions of files. With -R, make the change recursively through the directory structure. The user must be the owner of the file, or else a super-user. Additional information is in the HDFS Admin Guide: Permissions. Page 3 Copyright © 2008 The Apache Software Foundation. All rights reserved. HDFS File System Shell Guide 1.4. chown Usage: hadoop fs -chown [-R] [OWNER][:[GROUP]] URI [URI ] Change the owner of files. With -R, make the change recursively through the directory structure. The user must be a super-user. Additional information is in the HDFS Admin Guide: Permissions. 1.5. copyFromLocal Usage: hadoop fs -copyFromLocal URI Similar to put command, except that the source is restricted to a local file reference. 1.6. copyToLocal Usage: hadoop fs -copyToLocal [-ignorecrc] [-crc] URI Similar to get command, except that the destination is restricted to a local file reference. 1.7. count Usage: hadoop fs -count [-q] Count the number of directories, files and bytes under the paths that match the specified file pattern. The output columns are: DIR_COUNT, FILE_COUNT, CONTENT_SIZE FILE_NAME. The output columns with -q are: QUOTA, REMAINING_QUATA, SPACE_QUOTA, REMAINING_SPACE_QUOTA, DIR_COUNT, FILE_COUNT, CONTENT_SIZE, FILE_NAME. Example: • hadoop fs -count hdfs://nn1.example.com/file1 hdfs://nn2.example.com/file2 • hadoop fs -count -q hdfs://nn1.example.com/file1 Exit Code: Returns 0 on success and -1 on error. 1.8. cp Page 4 Copyright © 2008 The Apache Software Foundation. All rights reserved. HDFS File System Shell Guide Usage: hadoop fs -cp URI [URI …] Copy files from source to destination. This command allows multiple sources as well in which case the destination must be a directory. Example: • hadoop fs -cp /user/hadoop/file1 /user/hadoop/file2 • hadoop fs -cp /user/hadoop/file1 /user/hadoop/file2 /user/hadoop/dir Exit Code: Returns 0 on success and -1 on error. 1.9. du Usage: hadoop fs -du URI [URI …] Displays aggregate length of files contained in the directory or the length of a file in case its just a file. Example: hadoop fs -du /user/hadoop/dir1 /user/hadoop/file1 hdfs://nn.example.com/user/hadoop/dir1 Exit Code: Returns 0 on success and -1 on error. 1.10. dus Usage: hadoop fs -dus Displays a summary of file lengths. 1.11. expunge Usage: hadoop fs -expunge Empty the Trash. Refer to HDFS Architecture for more information on Trash feature. 1.12. get Usage: hadoop fs -get [-ignorecrc] [-crc] Copy files to the local file system. Files that fail the CRC check may be copied with the -ignorecrc option. Files and CRCs may be copied using the -crc option. Page 5 Copyright © 2008 The Apache Software Foundation. All rights reserved. HDFS File System Shell Guide Example: • hadoop fs -get /user/hadoop/file localfile • hadoop fs -get hdfs://nn.example.com/user/hadoop/file localfile Exit Code: Returns 0 on success and -1 on error. 1.13. getmerge Usage: hadoop fs -getmerge [addnl] Takes a source directory and a destination file as input and concatenates files in src into the destination local file. Optionally addnl can be set to enable adding a newline character at the end of each file. 1.14. ls Usage: hadoop fs -ls For a file returns stat on the file with the following format: permissions number_of_replicas userid groupid filesize modification_date modification_time filename For a directory it returns list of its direct children as in unix.A directory is listed as: permissions userid groupid modification_date modification_time dirname Example: hadoop fs -ls /user/hadoop/file1 Exit Code: Returns 0 on success and -1 on error. 1.15. lsr Usage: hadoop fs -lsr Recursive version of ls. Similar to Unix ls -R. Page 6 Copyright © 2008 The Apache Software Foundation. All rights reserved. HDFS File System Shell Guide 1.16. mkdir Usage: hadoop fs -mkdir Takes path uri's as argument and creates directories. The behavior is much like unix mkdir -p creating parent directories along the path. Example: • hadoop fs -mkdir /user/hadoop/dir1 /user/hadoop/dir2 • hadoop fs -mkdir hdfs://nn1.example.com/user/hadoop/dir hdfs://nn2.example.com/user/hadoop/dir Exit Code: Returns 0 on success and -1 on error. 1.17. moveFromLocal Usage: dfs -moveFromLocal Similar to put command, except that the source localsrc is deleted after it's copied. 1.18. moveToLocal Usage: hadoop fs -moveToLocal [-crc] Displays a "Not implemented yet" message. 1.19. mv Usage: hadoop fs -mv URI [URI …] Moves files from source to destination. This command allows multiple sources as well in which case the destination needs to be a directory. Moving files across filesystems is not permitted. Example: • hadoop fs -mv /user/hadoop/file1 /user/hadoop/file2 • hadoop fs -mv hdfs://nn.example.com/file1 hdfs://nn.example.com/file2 hdfs://nn.example.com/file3 hdfs://nn.example.com/dir1 Exit Code: Page 7 Copyright © 2008 The Apache Software Foundation. All rights reserved. HDFS File System Shell Guide Returns 0 on success and -1 on error. 1.20. put Usage: hadoop fs -put ... Copy single src, or multiple srcs from local file system to the destination filesystem. Also reads input from stdin and writes to destination filesystem. • hadoop fs -put localfile /user/hadoop/hadoopfile • hadoop fs -put localfile1 localfile2 /user/hadoop/hadoopdir • hadoop fs -put localfile hdfs://nn.example.com/hadoop/hadoopfile • hadoop fs -put - hdfs://nn.example.com/hadoop/hadoopfile Reads the input from stdin. Exit Code: Returns 0 on success and -1 on error. 1.21. rm Usage: hadoop fs -rm [-skipTrash] URI [URI …] Delete files specified as args. Only deletes non empty directory and files. If the -skipTrash option is specified, the trash, if enabled, will be bypassed and the specified file(s) deleted immediately. This can be useful when it is necessary to delete files from an over-quota directory. Refer to rmr for recursive deletes. Example: • hadoop fs -rm hdfs://nn.example.com/file /user/hadoop/emptydir Exit Code: Returns 0 on success and -1 on error. 1.22. rmr Usage: hadoop fs -rmr [-skipTrash] URI [URI …] Recursive version of delete. If the -skipTrash option is specified, the trash, if enabled, will be bypassed and the specified file(s) deleted immediately. This can be useful when it is necessary to delete files from an over-quota directory. Page 8 Copyright © 2008 The Apache Software Foundation. All rights reserved. HDFS File System Shell Guide Example: • hadoop fs -rmr /user/hadoop/dir • hadoop fs -rmr hdfs://nn.example.com/user/hadoop/dir Exit Code: Returns 0 on success and -1 on error. 1.23. setrep Usage: hadoop fs -setrep [-R] Changes the replication factor of a file. -R option is for recursively increasing the replication factor of files within a directory. Example: • hadoop fs -setrep -w 3 -R /user/hadoop/dir1 Exit Code: Returns 0 on success and -1 on error. 1.24. stat Usage: hadoop fs -stat URI [URI …] Returns the stat information on the path. Example: • hadoop fs -stat path Exit Code: Returns 0 on success and -1 on error. 1.25. tail Usage: hadoop fs -tail [-f] URI Displays last kilobyte of the file to stdout. -f option can be used as in Unix. Example: • hadoop fs -tail pathname Exit Code: Page 9 Copyright © 2008 The Apache Software Foundation. All rights reserved. HDFS File System Shell Guide Returns 0 on success and -1 on error. 1.26. test Usage: hadoop fs -test -[ezd] URI Options: -e check to see if the file exists. Return 0 if true. -z check to see if the file is zero length. Return 0 if true. -d check to see if the path is directory. Return 0 if true. Example: • hadoop fs -test -e filename 1.27. text Usage: hadoop fs -text Takes a source file and outputs the file in text format. The allowed formats are zip and TextRecordInputStream. 1.28. touchz Usage: hadoop fs -touchz URI [URI …] Create a file of zero length. Example: • hadoop -touchz pathname Exit Code: Returns 0 on success and -1 on error. Page 10 Copyright © 2008 The Apache Software Foundation. All rights reserved.