Overview
The File System (FS) shell includes various shell-like commands that directly interact with Hadoop Distributed File System (HDFS) as well as other file systems that Hadoop supports,such as Local FS,HFTP FS,S3 FS,and others.The FS shell is invoked by:
bin/hadoop fs
All FS shell commands take path URIs as arguments. The URI format is scheme://authority/path. For HDFS the scheme is hdfs,and for the Local FS the scheme is file. The scheme and authority are optional. If not 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 the your configuration is set to point to hdfs://namenodehost).
Most of the commands in FS schell 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.
If HDFS is being used,hdfs dfs is a synonym.
appendToFile
Usage:hadoop fs -appendToFile ...
Append single src,or multiple srcs from local file system to the destination file system. Also reads input from stdin and appends to destination file system.
hadoop fs -appendToFile localfile /user/hadoop/hadoopfile
hadoop fs -appendToFile localfile1 localfile2 /user/hadoop/hadoopfile
hadoop fs -appendToFile localfile hdfs://nn.example.com/hadoop/hadoopfile
hadoop fs -appendToFile - hdfs://nn.example.com/hadoop/hadoopfile Reads the input from stdin
Exit code:
Return 0 on success and -1 on error.
cat
Usage:hadoop fs -cat [-ignoreCrc] URI [URI ...]
Copies source paths to stdout.
Options:
The -ignoreCrc option disables checksum verification.
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.
checksum
Usage:hadoop fs -checksum URI
Returns the checksum information of a file.
Example:
hadoop fs -checksum hdfs://nn1.example.com/file1
hadoop fs -checksum file:///ext/hosts
chgrp
Usage:hadoop fs -chgrp [-R] GROUP URI [URI ...]
Change group association of files. The user must be the owner of files, or else a super-user. Additional information is in the Permission Guide.
Options:
The -R option will make the chage recursively through the directory structure.
chomd
Usage:hadoop fs -chmod [-R] URI [URI...]
Change the permissions of ifles. With -R make the change recursively though the directory structure. The user must be the owner of the file,or else a ssuper-user. Additional information is in the Permission Guide.
Options:
The -R option will make the change recursively through the directory structure.
copyFromLocal
Usage:hadoop fs -copyFromLocal URI
Similar to he fs -put command,except the source is retricted to a local file reference.
Options:
-p: Preserves access and modification times,ownership and the permissions.(assuming the permissions can be propagated across filesystems)
-f: Overwrites the destination if it already exists.
-l: Allow DataNode to lazily persist the file to disk, Forces a rplication factor of 1. This flag will result in reduced durability. Use with care.
-d: Skip creation of temporary file with the suffix ._COPYING_.
copyToLocal
Usage:hadoop fs -copyToLocal [-ignorecrc] [-crc] URI
Similar to get command,except that the destination is restricted to a local file reference.
count
Usage: hadoop fs -count [-q] [-h] [-v]
Count the number of directories,files and bytes under the paths that match the specified file pattern. The output columns with -count are:DIR_COUNT,FILE_COUNT,CONTENT_SIZE,PATHNAME.
The output columns with -count -q are:QUOTA,REMAINING_QUOTA,REMAINING_SPACE_QUOTA,DIR_COUNT,FILE_COUNT,CONTENT_SIZE,PATHNAME.
The -h option shows sizes in human readable format.
The -v option displays a header line.
Example:
hadoop fs -count hdfs://nn1.example.com/file1 hdfs://nn2.example.com/file2
hadoop fs -count -q hdfs://nn1.example.com/file1
hadoop fs -count -q -h hdfs://nn1.example.com/file1
hadoop fs -count -q -h -v hdfs://nn1.example.com/file1
Exit Code:
Returns 0 on success and -1 on error.
cp
Usage:hadoop fs -cp [-f] [-p[topax]] URI [URI...]
Copy files from source to destination. This command allows multiple sources as well in which case the destination must be directory.
'raw.*' namespace extended attributes are preserved if(1) the source and destination filesystems support them(HDFS only),and(2) all source and destination pathnames are in the /.reserved/raw hierarchy. Determination of whether raw.*namespace xattrs are preserved is independent of the -p(preserve) flag.
Options:
The -f option will overwrite the destination if it is already exists.
The -p option will preserve file attributes[topx](timestamps,ownership,permission,ACL,XAttr).If -p is specified with no arg,then preserves timestamps,ownership,permission. If -pa is specified,the preserves permission also because ACL is a super-set of permission. Determination of whether raw namespace extended attributes are preserved is independent of the -p flag.
Example:
hadoop fs -cat -cp /user/hadoop/file1 /user/hadoop/file2
hadoop fs -cat -cp /user/hadoop/file1 /user/hadoop/file2 /user/hadoop/dir
Exit Code:
Returns 0 on success and -1 on error.
createSnapshot
See HDFS Snapshots Guide.
deleteSnapshot
See HDFS Snapshots Guide.
df
Usage: hadoop fs -df [-h] URI [URI...]
Displays free space.
Options:
The -h option will format file size in a "human-readable" fashion(e.g 64.0m instead of 67108864).
Example:
hadoop fs - df /user/hadoop/dir1
du
Usage:hadoop fs -du [-s] [-h] URI [URI...]
Displays sizes of files and directories contained in the given directory or the length of a file in case it is just a file.
Options:
The -s option will result in an aggregate summary of file lengths being displayed,rather than the individual files.
The -h option will format file sizes in a "human-readable" fashion(e.g 64.0m instead of 67108864)
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.
expunge
Usage:hadoop fs -expunge
Permanentlty delete files in checkpoints older than the retention threshold from trash directory,and create new checkpoint.
When checkpoint is created,recently deleted files in trash are moved under the checkpoint. Files in checkpoints older than fs.trash.checkpoint.interval will be permanently deleted on the next invocation of -expunge command.
If the file system supports the feature,users can configure to create and delete checkpoints periodically by the parameter stored as fs.trash.checkpoint.interval(in core-site.xml). This value should be smaller or equal to fs.trash.interval.
Refer to the HDFS Architecture guide for more information about trash feature of HDFS.
find
Usage:hadoop fs -find ... ...
Finds all files that match the specified expression and applies selected actions to them. If no path is specified then defaults to the current working directory. If no expression is specified then defaults to -print.
The following primary expressions are recognised:
-name pattern
-iname pattern
Evalusates as true if the basename of the file matches the pattern using standard file system globbing. If -iname is used then the match is acse insenstive.
-print0Alwasys
Evaluates to true. Causes the current pathname to be written to standard output. If the -print0 expression is used then an ASCII NULL character is appended.
The following operators are recognised:
expression -a expression
expression and expression
expression expression
Logical AND operator for joining two expressions. Returns true if both child expressions return true. Implied by the juxtaposition of two expressions and so does not need to be explicity specified. The second expression will not be applied if the first fails.
Example:
hadoop fs -find / -name test -print
Exit Code:
Returns 0 on success and -1 on error.
get
Usage:hadoop fs -get [-ignorecrc] [-crc] [-p] [-f]
Copy files to the local file system. Files that fail the CRC check may be copied eith the -ignorecrc options. Files and CRCs may be copied using the -crc option.
Example:
hadoop fs -get /user/hadoop/file localfile
hadoop fs -get hdfs://nn.example.com/user/hadoop/file localfile
Options:
-p:Preserves access and modification times,ownership and the permissions.(assuming the permissions can be propagated across filesytems)
-f:Overwrites the destination if it already exists.
-ignorecrc:Skip CRC checks on the file(s) download.
-crc:Write CRC checksums for the files download.
getfacl
Usage:hadoop fs -getfacl [-R]
Displays the Access Control Lists(ACLs) of files and directories. If a directory has a default ACL,then getfacl also displays the default ACL.
Options:
-R:List the ACLs of all files and directories recursively.
path:File or directory to list.
Example:
hadoop fs -getfacl /file
hadoop fs -getfacl -R /dir
Exit Code:
Returns 0 on success and -1 on error.
getmerge
Usage:hadoop fs -getmerge [-nl]
Takes a source directory and a destination file as input and concatenates files in src into the destination local file. Optionally -nl can be set to enable adding a newline character(LF) at the end of each file.
Example:
hadoop fs -getmerge -nl /src /opt/output.txt
hadoop fs -getmerge -nl /src/file1.txt /src/file2.txt /output.txt
Exit Code:
Returns 0 on success and noe-zero on error.
help
Usage:hadoop fs -help
Return usage output.
ls
Usage:hadoop fs -ls [-d] [-h] [-R]
Options:
-d:Directories are listed as plain files.
-h:Format file sizes in a human-readable fashion(e.g. 64.0m instead of 67108864).
-R:Recursively list subdirectories encountered.
For a file is 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
Files within a directory are order by file name by default.
Example:
hadoop fs -ls /user/hadoop/file1
Exit Code:
Returns 0 on success and -1 on error.
mkdir
Usage:hadoop fs -mkdir [-p]
Takes path uri is as argument and creates directories.
Options:
The -p option 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/hadoop/dir hdfs://nn1.example.com/user/hadoop/dir
Exit Code:
Return 0 on success and -1 on error.
moveFromLocal
Usage:hadoop fs -moveFromLocal
Similar to put command,except that the source localsrc is deleted after it is copied.
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 file systems 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/dir1
Exit Code:
Returns 0 on success and -1 on error.
put
Usage:hadoop fs -put [-f] [-p] [-l] [-d] [ - | ...]
Copy single src,or multiple srcs from local file system to destination file system. Also reads input from stdin and writes to destination file system if the source is set to "-".
Copying fails if the file already exists,unless the -f flag is given.
Options:
-p:Preserves access and modification times,ownership and permissions.(assuming the permissions can be propagated across filesystems)
-f:Overwrites the destination if it already exists.
-l:Allow DataNode to lazily persist the file to disk,Forces a replication factor of 1. This flag will result in reduced durability. Use with care.
-d:Skip creation of temporary file with the suffix ._COPYING_.
Example:
hadoop fs -put localfile /user/hadoop/hadoopfile
hadoop fs -put -f localfile1 localfile2 /user/hadoop/hadoopdir
hadoop fs -put -d 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.
rm
Usage:hadoop fs -rm [-f] [-r] [-R] [-skipTrash] URI [URI ...]
Delete files specified as args.
If trash is enabled,file system instead moves the deleted file to a trash directory(tiven by FileSystem#getTrashRoot).
Currently,the trash feature is disabled by default. User can enable trash by setting a value greater then zero for parameter fs.trash.interval()in core-site.xml.
See expunge about deletion of files trash.
Options:
The -f option will not display a diagnostic message or modify the exit status to reflect an error if the file does not exist.
The -R option deletes the directory and any content under it recursively.
The -r option is equivalent to -R.
The -skipTrash option will bypass trash,if enabled,and delete the specified files immediately. This can be useful when it is necessary to delete files from an over-quota directory.
Example:
hadoop fs -rm hdfs://nn.example.com/file /user/hadoop/emptydir
Exit Code:
Returns 0 on success and -1 on error.
rmdir
Usage:hadoop fs -rmdir [--ignore-fail-on-non-empty] URI [URI ...]
Delete a directory.
Options:
--ignore-fail-on-non-empty:When usring wildcards,do not fail if a directory still contais files.
Example:
hadoop fs -rmdir /user/hadoop/emptydir
setfacl
Usage:hadoop fs -setfacl [-R] [-b | -k -m | -x ]
Sets Access Control Lists(ACLs) of files and directories.
Options:
-b:Remove all but the base ACL entries. The entries for user,group and others are retained for compatibility with permission bits.
-k:Remove the default ACL.
-R:Apply operations to all files and directories recursively.
-m:Modify ACL New entries. Other ACL entries are retained.
--set:Fully replace the ACL,discarding all existing entries. The acl_spec must include entries for user,group,and others for compatibility with permission bits.
acl_spec:Comma Separated list of ACL entries.
path:File or directory to modify.
Example:
hadoop fs -setfacl -m user:hadoop:rw- /file
hadoop fs -setfacl -x user:hadoop /file
hadoop fs -setfacl -b /file
hadoop fs -setfacl -k /dir
hadoop fs -setfacl --set user:rw-,user:hadoop:rw-,group::r--,other::r-- /file
hadoop fs -setfacl -R -m user:hadoop:r-x /dir
hadoop fs -setfacl -m default:user:hadoop:r-x /dir
Exit Code:
Return 0 on success and non-zero on error.
setfattr
Usage:hadoop fs -setfattr -n name [-v value] -x name
Sets and extended attribute name and value for a file or directory.
Options:
-n name:The extended attribute name.
-v vlaue:The extended attribute value. There are three different encoding methods for the value. If the argument is enclosed in double quotes,the the value is the string inside the quotes. If the argument is prefixed with 0x or 0X,then it taken as a hexadecimal number. If the argument begins with 0s or 0S,then it taken a base64 encoding.
-x name:Remove the extended attribute.
path:The file or diretory.
Example:
hadoop fs -setfattr -n user.myAttr -v myValue /file
hadoop fs -setfattr -n user.noValue /file
hadoop fs -setfattr -x user.myAttr /file
Exit Code:
Returns 0 on success and -1 on error.
setrep
Usage:hadoop fs -setrep [-R] [-w]
Changes the replication factor of a file. If path is a directory then the command recursively changes the replication factor of all files under the directory tree rooted at path.
Options:
The -w flag requests that command wait for the replication to complete. This can potentially take a very long time.
The -R flag is accepted for backwards compatibility. It has no effect.
Example:
hadoop fs -setrep -w 3 /user/hadoop/dir1
Exit Code:
Returns 0 on success and -1 on error.
stat
Usage:hadoop fs -stat [format] ...
Print statistics ablout file/directory at in the specified format. Format accepts filesize in blocks(%b),type(%F),group name of owner(%g),name(%n),block size(%o),replication(%r),user name of owner(%u),and modification date(%y,%Y). %y show UTC date as "yyyy-MM-dd HH:mm:ss" and %Y shows milliseconds since January 1,1970 UTC. If the format is not specified,%y is used by default.
Exmaple:
hadoop fs - stat "%F %u:%g %b %y %n" /file
Exit Code:
Returns 0 on success and -1 on error.
tail
Usage:hadoop fs -tail [-f] URI
Displays last kilobyte of the file to stdout.
Options:
The -f option will output appended data as the file grows,as in Unix.
Example:
hadoop fs -tail pathname
Exit Code:
Returns 0 on success and -1 on error.
test
Usage:hadoop fs -test -[defsz] URI
Options:
-d:if the path is a directory,return 0.
-e:if the path exists,return 0.
-f:if the path is a file,return 0.
-s:if the path is not empty,return 0.
-z:if the path is zero length,return 0.
Example:
hadoop fs -test -e filename
text
Usage:hadoop fs -text
Takes a source file and outputs the file in the text format. The allowed formats are zip and TextRecordInputStream.
touchz
Usage:hadoop fs -touchz URI [URI ...]
Create a file of zero length. An error is returned if the file exists with non-zero length.
Example:
hadoop fs -touchz pathname
Exit Code:
Returns 0 on success and -1 on error.
truncate
Usage:hadoop fs -truncate [-w]
Truncate all files that match the specified file pattern to the specifiled length.
Options:
Thw -w flag requests that the command waits for block recovery to complete, if necessary. Without -w flag the file may remain unclosed for some time while the recovery is in progress. During this time file can not be reopened for append.
Example:
hadoop fs -truncate 55 /user/hadoop/file1 /user/hadoop/file2
hadoop fs -truncate -w 127 hdfs://nn1.example.com/user/hadoop/file1
usage
Usage:hadoop fs -usage command
Return the help for an individual command.
