The File System (FS) shell includes various shell-like commands that directly interact with the 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 <args>
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, 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.
If HDFS is being used, hdfs dfs is a synonym.
Relative paths can be used. For HDFS, the current working directory is the HDFS home directory /user/<username> that often has to be created manually. The HDFS home directory can also be implicitly accessed, e.g., when using the HDFS trash folder, the .Trash directory in the home directory.
See the Commands Manual for generic shell options.
Usage: hadoop fs -appendToFile <localsrc> ... <dst>
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.
Exit Code:
Returns 0 on success and 1 on error.
Usage: hadoop fs -cat [-ignoreCrc] URI [URI ...]
Copies source paths to stdout.
Options
Example:
Exit Code:
Returns 0 on success and -1 on error.
Usage: hadoop fs -checksum URI
Returns the checksum information of a file.
Example:
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 Permissions Guide.
Options
Usage: hadoop fs -chmod [-R] <MODE[,MODE]... | OCTALMODE> 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 Permissions Guide.
Options
Usage: hadoop fs -chown [-R] [OWNER][:[GROUP]] URI [URI ]
Change the owner of files. The user must be a super-user. Additional information is in the Permissions Guide.
Options
Usage: hadoop fs -copyFromLocal <localsrc> URI
Similar to the fs -put command, except that the source is restricted to a local file reference.
Options:
Usage: hadoop fs -copyToLocal [-ignorecrc] [-crc] URI <localdst>
Similar to get command, except that the destination is restricted to a local file reference.
Usage: hadoop fs -count [-q] [-h] [-v] [-x] [-t [<storage type>]] [-u] <paths>
Count the number of directories, files and bytes under the paths that match the specified file pattern. Get the quota and the usage. The output columns with -count are: DIR_COUNT, FILE_COUNT, CONTENT_SIZE, PATHNAME
The -u and -q options control what columns the output contains. -q means show quotas, -u limits the output to show quotas and usage only.
The output columns with -count -q are: QUOTA, REMAINING_QUOTA, SPACE_QUOTA, REMAINING_SPACE_QUOTA, DIR_COUNT, FILE_COUNT, CONTENT_SIZE, PATHNAME
The output columns with -count -u are: QUOTA, REMAINING_QUOTA, SPACE_QUOTA, REMAINING_SPACE_QUOTA
The -t option shows the quota and usage for each storage type. The -t option is ignored if -u or -q option is not given. The list of possible parameters that can be used in -t option(case insensitive except the parameter "“): ”“, ”all“, ”ram_disk“, ”ssd“, ”disk“ or ”archive".
The -h option shows sizes in human readable format.
The -v option displays a header line.
The -x option excludes snapshots from the result calculation. Without the -x option (default), the result is always calculated from all INodes, including all snapshots under the given path. The -x option is ignored if -u or -q option is given.
Example:
Exit Code:
Returns 0 on success and -1 on error.
Usage: hadoop fs -cp [-f] [-p | -p[topax]] URI [URI ...] <dest>
Copy files from source to destination. This command allows multiple sources as well in which case the destination must be a 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:
Example:
Exit Code:
Returns 0 on success and -1 on error.
See HDFS Snapshots Guide.
See HDFS Snapshots Guide.
Usage: hadoop fs -df [-h] URI [URI ...]
Displays free space.
Options:
Example:
Usage: hadoop fs -du [-s] [-h] [-x] URI [URI ...]
Displays sizes of files and directories contained in the given directory or the length of a file in case its just a file.
Options:
The du returns three columns with the following format:
size disk_space_consumed_with_all_replicas full_path_name
Example:
Exit Code: Returns 0 on success and -1 on error.
Usage: hadoop fs -dus <args>
Displays a summary of file lengths.
Note: This command is deprecated. Instead use hadoop fs -du -s.
Usage: hadoop fs -expunge
Permanently 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.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.
Usage: hadoop fs -find <path> ... <expression> ...
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
Evaluates as true if the basename of the file matches the pattern using standard file system globbing. If -iname is used then the match is case insensitive.
-print
-print0
Always 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 explicitly 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.
Usage: hadoop fs -get [-ignorecrc] [-crc] [-p] [-f] <src> <localdst>
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.
Example:
Exit Code:
Returns 0 on success and -1 on error.
Options:
Usage: hadoop fs -getfacl [-R] <path>
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:
Examples:
Exit Code:
Returns 0 on success and non-zero on error.
Usage: hadoop fs -getfattr [-R] -n name | -d [-e en] <path>
Displays the extended attribute names and values (if any) for a file or directory.
Options:
Examples:
Exit Code:
Returns 0 on success and non-zero on error.
Usage: hadoop fs -getmerge [-nl] <src> <localdst>
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. -skip-empty-file can be used to avoid unwanted newline characters in case of empty files.
Examples:
Exit Code:
Returns 0 on success and non-zero on error.
Usage: hadoop fs -ls [-C] [-d] [-h] [-q] [-R] [-t] [-S] [-r] [-u] <args>
Options:
For a file ls 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 filename by default.
Example:
Exit Code:
Returns 0 on success and -1 on error.
Usage: hadoop fs -lsr <args>
Recursive version of ls.
Note: This command is deprecated. Instead use hadoop fs -ls -R
Usage: hadoop fs -mkdir [-p] <paths>
Takes path uri’s as argument and creates directories.
Options:
Example:
Exit Code:
Returns 0 on success and -1 on error.
Usage: hadoop fs -moveFromLocal <localsrc> <dst>
Similar to put command, except that the source localsrc is deleted after it’s copied.
Usage: hadoop fs -moveToLocal [-crc] <src> <dst>
Displays a “Not implemented yet” message.
Usage: hadoop fs -mv URI [URI ...] <dest>
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:
Exit Code:
Returns 0 on success and -1 on error.
Usage: hadoop fs -put [-f] [-p] [-l] [-d] [ - | <localsrc1> .. ]. <dst>
Copy single src, or multiple srcs from local file system to the 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:
Examples:
Exit Code:
Returns 0 on success and -1 on error.
See HDFS Snapshots Guide.
Usage: hadoop fs -rm [-f] [-r |-R] [-skipTrash] [-safely] URI [URI ...]
Delete files specified as args.
If trash is enabled, file system instead moves the deleted file to a trash directory (given by FileSystem#getTrashRoot).
Currently, the trash feature is disabled by default. User can enable trash by setting a value greater than zero for parameter fs.trash.interval (in core-site.xml).
See expunge about deletion of files in trash.
Options:
Example:
Exit Code:
Returns 0 on success and -1 on error.
Usage: hadoop fs -rmdir [--ignore-fail-on-non-empty] URI [URI ...]
Delete a directory.
Options:
Example:
Usage: hadoop fs -rmr [-skipTrash] URI [URI ...]
Recursive version of delete.
Note: This command is deprecated. Instead use hadoop fs -rm -r
Usage: hadoop fs -setfacl [-R] [-b |-k -m |-x <acl_spec> <path>] |[--set <acl_spec> <path>]
Sets Access Control Lists (ACLs) of files and directories.
Options:
Examples:
Exit Code:
Returns 0 on success and non-zero on error.
Usage: hadoop fs -setfattr -n name [-v value] | -x name <path>
Sets an extended attribute name and value for a file or directory.
Options:
Examples:
Exit Code:
Returns 0 on success and non-zero on error.
Usage: hadoop fs -setrep [-R] [-w] <numReplicas> <path>
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:
Example:
Exit Code:
Returns 0 on success and -1 on error.
Usage: hadoop fs -stat [format] <path> ...
Print statistics about the file/directory at <path> 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 shows 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.
Example:
Exit Code: Returns 0 on success and -1 on error.
Usage: hadoop fs -tail [-f] URI
Displays last kilobyte of the file to stdout.
Options:
Example:
Exit Code: Returns 0 on success and -1 on error.
Usage: hadoop fs -test -[defsz] URI
Options:
Example:
Usage: hadoop fs -text <src>
Takes a source file and outputs the file in text format. The allowed formats are zip and TextRecordInputStream.
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:
Exit Code: Returns 0 on success and -1 on error.
Usage: hadoop fs -truncate [-w] <length> <paths>
Truncate all files that match the specified file pattern to the specified length.
Options:
Example:
Usage: hadoop fs -usage command
Return the help for an individual command.
The Hadoop FileSystem shell works with Object Stores such as Amazon S3, Azure WASB and OpenStack Swift.
# Create a directory hadoop fs -mkdir s3a://bucket/datasets/ # Upload a file from the cluster filesystem hadoop fs -put /datasets/example.orc s3a://bucket/datasets/ # touch a file hadoop fs -touchz wasb://yourcontainer@youraccount.blob.core.windows.net/touched
Unlike a normal filesystem, renaming files and directories in an object store usually takes time proportional to the size of the objects being manipulated. As many of the filesystem shell operations use renaming as the final stage in operations, skipping that stage can avoid long delays.
In particular, the put and copyFromLocal commands should both have the -d options set for a direct upload.
# Upload a file from the cluster filesystem hadoop fs -put -d /datasets/example.orc s3a://bucket/datasets/ # Upload a file from under the user's home directory in the local filesystem. # Note it is the shell expanding the "~", not the hadoop fs command hadoop fs -copyFromLocal -d -f ~/datasets/devices.orc s3a://bucket/datasets/ # create a file from stdin # the special "-" source means "use stdin" echo "hello" | hadoop fs -put -d -f - wasb://yourcontainer@youraccount.blob.core.windows.net/hello.txt
Objects can be downloaded and viewed:
# copy a directory to the local filesystem hadoop fs -copyToLocal s3a://bucket/datasets/ # copy a file from the object store to the cluster filesystem. hadoop fs -get wasb://yourcontainer@youraccount.blob.core.windows.net/hello.txt /examples # print the object hadoop fs -cat wasb://yourcontainer@youraccount.blob.core.windows.net/hello.txt # print the object, unzipping it if necessary hadoop fs -text wasb://yourcontainer@youraccount.blob.core.windows.net/hello.txt ## download log files into a local file hadoop fs -getmerge wasb://yourcontainer@youraccount.blob.core.windows.net/logs\* log.txt
Commands which list many files tend to be significantly slower than when working with HDFS or other filesystems
hadoop fs -count s3a://bucket/ hadoop fs -du s3a://bucket/
Other slow commands include find, mv, cp and rm.
Find
This can be very slow on a large store with many directories under the path supplied.
# enumerate all files in the object store's container. hadoop fs -find s3a://bucket/ -print # remember to escape the wildcards to stop the shell trying to expand them first hadoop fs -find s3a://bucket/datasets/ -name \*.txt -print
Rename
The time to rename a file depends on its size.
The time to rename a directory depends on the number and size of all files beneath that directory.
hadoop fs -mv s3a://bucket/datasets s3a://bucket/historical
If the operation is interrupted, the object store will be in an undefined state.
Copy
hadoop fs -cp s3a://bucket/datasets s3a://bucket/historical
The copy operation reads each file and then writes it back to the object store; the time to complete depends on the amount of data to copy, and the bandwidth in both directions between the local computer and the object store.
The further the computer is from the object store, the longer the copy takes
The rm command will delete objects and directories full of objects. If the object store is eventually consistent, fs ls commands and other accessors may briefly return the details of the now-deleted objects; this is an artifact of object stores which cannot be avoided.
If the filesystem client is configured to copy files to a trash directory, this will be in the bucket; the rm operation will then take time proportional to the size of the data. Furthermore, the deleted files will continue to incur storage costs.
To avoid this, use the the -skipTrash option.
hadoop fs -rm -skipTrash s3a://bucket/dataset
Data moved to the .Trash directory can be purged using the expunge command. As this command only works with the default filesystem, it must be configured to make the default filesystem the target object store.
hadoop fs -expunge -D fs.defaultFS=s3a://bucket/
If an object store is eventually consistent, then any operation which overwrites existing objects may not be immediately visible to all clients/queries. That is: later operations which query the same object’s status or contents may get the previous object. This can sometimes surface within the same client, while reading a single object.
Avoid having a sequence of commands which overwrite objects and then immediately work on the updated data; there is a risk that the previous data will be used instead.
Timestamps of objects and directories in Object Stores may not follow the behavior of files and directories in HDFS.
Consult the DistCp documentation for details on how this may affect the distcp -update operation.
The security and permissions models of object stores are usually very different from those of a Unix-style filesystem; operations which query or manipulate permissions are generally unsupported.
Operations to which this applies include: chgrp, chmod, chown, getfacl, and setfacl. The related attribute commands getfattr andsetfattr are also usually unavailable.
Filesystem commands which list permission and user/group details, usually simulate these details.
Operations which try to preserve permissions (example fs -put -p) do not preserve permissions for this reason. (Special case: wasb://, which preserves permissions but does not enforce them).
When interacting with read-only object stores, the permissions found in “list” and “stat” commands may indicate that the user has write access, when in fact they do not.
Object stores usually have permissions models of their own, models can be manipulated through store-specific tooling. Be aware that some of the permissions which an object store may provide (such as write-only paths, or different permissions on the root path) may be incompatible with the Hadoop filesystem clients. These tend to require full read and write access to the entire object store bucket/container into which they write data.
As an example of how permissions are mocked, here is a listing of Amazon’s public, read-only bucket of Landsat images:
$ hadoop fs -ls s3a://landsat-pds/ Found 10 items drwxrwxrwx - mapred 0 2016-09-26 12:16 s3a://landsat-pds/L8 -rw-rw-rw- 1 mapred 23764 2015-01-28 18:13 s3a://landsat-pds/index.html drwxrwxrwx - mapred 0 2016-09-26 12:16 s3a://landsat-pds/landsat-pds_stats -rw-rw-rw- 1 mapred 105 2016-08-19 18:12 s3a://landsat-pds/robots.txt -rw-rw-rw- 1 mapred 38 2016-09-26 12:16 s3a://landsat-pds/run_info.json drwxrwxrwx - mapred 0 2016-09-26 12:16 s3a://landsat-pds/runs -rw-rw-rw- 1 mapred 27458808 2016-09-26 12:16 s3a://landsat-pds/scene_list.gz drwxrwxrwx - mapred 0 2016-09-26 12:16 s3a://landsat-pds/tarq drwxrwxrwx - mapred 0 2016-09-26 12:16 s3a://landsat-pds/tarq_corrupt drwxrwxrwx - mapred 0 2016-09-26 12:16 s3a://landsat-pds/test
When an attempt is made to delete one of the files, the operation fails —despite the permissions shown by the ls command:
$ hadoop fs -rm s3a://landsat-pds/scene_list.gz rm: s3a://landsat-pds/scene_list.gz: delete on s3a://landsat-pds/scene_list.gz: com.amazonaws.services.s3.model.AmazonS3Exception: Access Denied (Service: Amazon S3; Status Code: 403; Error Code: AccessDenied; Request ID: 1EF98D5957BCAB3D), S3 Extended Request ID: wi3veOXFuFqWBUCJgV3Z+NQVj9gWgZVdXlPU4KBbYMsw/gA+hyhRXcaQ+PogOsDgHh31HlTCebQ=
This demonstrates that the listed permissions cannot be taken as evidence of write access; only object manipulation can determine this.
Note that the Microsoft Azure WASB filesystem does allow permissions to be set and checked, however the permissions are not actually enforced. This feature offers the ability for a HDFS directory tree to be backed up with DistCp, with its permissions preserved, permissions which may be restored when copying the directory back into HDFS. For securing access to the data in the object store, however, Azure’s own model and tools must be used.
Here is the list of shell commands which generally have no effect —and may actually fail.
| command | limitations |
|---|---|
| appendToFile | generally unsupported |
| checksum | the usual checksum is “NONE” |
| chgrp | generally unsupported permissions model; no-op |
| chmod | generally unsupported permissions model; no-op |
| chown | generally unsupported permissions model; no-op |
| createSnapshot | generally unsupported |
| deleteSnapshot | generally unsupported |
| df | default values are normally displayed |
| getfacl | may or may not be supported |
| getfattr | generally supported |
| renameSnapshot | generally unsupported |
| setfacl | generally unsupported permissions model |
| setfattr | generally unsupported permissions model |
| setrep | has no effect |
| truncate | generally unsupported |
Different object store clients may support these commands: do consult the documentation and test against the target store.