Command Line Interface

Alluxio’s command line interface provides users with basic file system operations. You can invoke the command line utility using:

./bin/alluxio fs

All “path” variables in fs commands should start with

alluxio://<master node address>:<master node port>/<path>

Or, if no header is provided, the default hostname and port (set in the env file) will be used.

/<path>

Wildcard Input

Most of the commands which require path components allow wildcard arguments for ease of use. For example:

./bin/alluxio fs rm /data/2014*

The example command would delete anything in the data directory with a prefix of 2014.

Note that some shells will attempt to glob the input paths, causing strange errors (Note: the number 21 could be different and comes from the number of matching files in your local filesystem):

rm takes 1 arguments,  not 21

As a work around, you can disable globbing (depending on your shell, for example set -f) or by escaping wildcards, for example:

./bin/alluxio fs cat /\\*

Note the double escape, this is because the shell script will eventually call a java program which should have the final escaped parameters (cat /\*).

List of Operations

Example Use Cases

cat

The cat command prints the entire contents of a file in Alluxio to the console. This can be useful for verifying the file is what the user expects. If you wish to copy the file to your local file system, copyToLocal should be used.

For example, when trying out a new computation job, cat can be used as a quick way to check the output:

./bin/alluxio fs cat /output/part-00000

checkConsistency

The checkConsistency command compares Alluxio and under storage metadata for a given path. If the path is a directory, the entire subtree will be compared. The command returns a message listing each inconsistent file or directory. The system administrator should reconcile the differences of these files at their discretion. To avoid metadata inconsistencies between Alluxio and under storages, design your systems to modify files and directories through the Alluxio and avoid directly modifying state in the underlying storage.

NOTE: This command requires a read lock on the subtree being checked, meaning writes and updates to files or directories in the subtree cannot be completed until this command completes.

For example, checkConsistency can be used to periodically validate the integrity of the namespace.

./bin/alluxio fs checkConsistency /

checksum

The checksum command outputs the md5 value of a file in Alluxio.

For example, checksum can be used to verify the content of a file stored in Alluxio matches the content stored in an UnderFS or local filesystem:

./bin/alluxio fs checksum /LICENSE
md5sum: bf0513403ff54711966f39b058e059a3
md5 LICENSE
MD5 (LICENSE) = bf0513403ff54711966f39b058e059a3

chgrp

The chgrp command changes the group of the file or directory in Alluxio. Alluxio supports file authorization with Posix file permission. Group is an authorizable entity in Posix file permission model. The file owner or super-user can execute this command to change the group of the file or directory.

Adding -R option also changes the group of child file and child directory recursively.

For example, chgrp can be used as a quick way to change the group of file:

./bin/alluxio fs chgrp alluxio-group-new /input/file1

chmod

The chmod command changes the permission of file or directory in Alluxio. Currently octal mode is supported: the numerical format accepts three octal digits which refer to permissions for the file owner, the group and other users. Here is number-permission mapping table:

Adding -R option also changes the permission of child file and child directory recursively.

For example, chmod can be used as a quick way to change the permission of file:

./bin/alluxio fs chmod 755 /input/file1

chown

The chown command changes the owner of the file or directory in Alluxio. For obvious security reasons, the ownership of a file can only be altered by a super-user.

Adding -R option also changes the owner of child file and child directory recursively.

For example, chown can be used as a quick way to change the owner of file:

./bin/alluxio fs chown alluxio-user /input/file1

copyFromLocal

The copyFromLocal command copies the contents of a file in your local file system into Alluxio. If the node you run the command from has an Alluxio worker, the data will be available on that worker. Otherwise, the data will be copied to a random remote node running an Alluxio worker. If a directory is specified, the directory and all its contents will be copied recursively.

For example, copyFromLocal can be used as a quick way to inject data into the system for processing:

./bin/alluxio fs copyFromLocal /local/data /input

copyToLocal

The copyToLocal command copies the contents of a file in Alluxio to a file in your local file system. If a directory is specified, the directory and all its contents will be downloaded recurisvely.

For example, copyToLocal can be used as a quick way to download output data for additional investigation or debugging.

./bin/alluxio fs copyToLocal /output/part-00000 part-00000
wc -l part-00000

count

The count command outputs the number of files and folders matching a prefix as well as the total size of the files. count works recursively and accounts for any nested directories and files. count is best utilized when the user has some predefined naming conventions for their files.

For example, if data files are stored by their date, count can be used to determine the number of data files and their total size for any date, month, or year.

./bin/alluxio fs count /data/2014

cp

The cp command copies a file or directory in the Alluxio filesystem.

If the -R option is used and the source designates a directory, cp copies the entire subtree at source to the destination.

For example, cp can be used to copy files between Under file systems.

./bin/alluxio fs cp /hdfs/file1 /s3/

du

The du command outputs the size of a file. If a directory is specified, it will output the aggregate size of all files in the directory and its children directories.

For example, if the Alluxio space is unexpectedly over utilized, du can be used to detect which folders are taking up the most space.

./bin/alluxio fs du /\\*

fileInfo

The fileInfo command dumps the FileInfo representation of a file to the console. It is primarily intended to assist powerusers in debugging their system. Generally viewing the file info in the UI will be much easier to understand.

For example, fileInfo can be used to debug the block locations of a file. This is useful when trying to achieve locality for compute workloads.

./bin/alluxio fs fileInfo /data/2015/logs-1.txt

free

The free command sends a request to the master to evict all blocks of a file from the Alluxio workers. If the argument to free is a directory, it will recursively free all files. This request is not guaranteed to take effect immediately, as readers may be currently using the blocks of the file. Free will return immediately after the request is acknowledged by the master. Note that free does not delete any data from the under storage system, and only affects data stored in Alluxio space. In addition, metadata will not be affected by this operation, meaning the freed file will still show up if an ls command is run.

For example, free can be used to manually manage Alluxio’s data caching.

./bin/alluxio fs free /unused/data

getCapacityBytes

The getCapacityBytes command returns the maximum number of bytes Alluxio is configured to store.

For example, getCapacityBytes can be used to verify if your cluster is set up as expected.

./bin/alluxio fs getCapacityBytes

getUsedBytes

The getUsedBytes command returns the number of used bytes in Alluxio.

For example, getUsedBytes can be used to monitor the health of your cluster.

./bin/alluxio fs getUsedBytes

leader

The leader command prints the current Alluxio leader master host name.

./bin/alluxio fs leader

load

The load command moves data from the under storage system into Alluxio storage. If there is a Alluxio worker on the machine this command is run from, the data will be loaded to that worker. Otherwise, a random worker will be selected to serve the data. Load will no-op if the file is already in Alluxio memory level storage. If load is run on a directory, files in the directory will be recursively loaded.

For example, load can be used to prefetch data for analytics jobs.

./bin/alluxio fs load /data/today

loadMetadata

The loadMetadata command is deprecated since Alluxio version 1.1. Please use alluxio fs ls <path> command instead.

The loadMetadata command queries the under storage system for any file or directory matching the given path and then creates a mirror of the file in Alluxio backed by that file. Only the metadata, such as the file name and size are loaded this way and no data transfer occurs.

For example, loadMetadata can be used when other systems output to the under storage directly (bypassing Alluxio), and the application running on Alluxio needs to use the output of those systems.

./bin/alluxio fs loadMetadata /hdfs/data/2015/logs-1.txt

location

The location command returns the addresses of all the Alluxio workers which contain blocks belonging to the given file.

For example, location can be used to debug data locality when running jobs using a compute framework.

./bin/alluxio fs location /data/2015/logs-1.txt

ls

The ls command lists all the immediate children in a directory and displays the file size, last modification time, and in memory status of the files. Using ls on a file will only display the information for that specific file.

Adding -R option also recursively lists child directories, displaying the entire subtree starting from the input path.

The ls command will also load the metadata for any file or directory from the under storage system to Alluxio namespace, if it does not exist in Alluxio yet. ls queries the under storage system for any file or directory matching the given path and then creates a mirror of the file in Alluxio backed by that file. Only the metadata, such as the file name and size are loaded this way and no data transfer occurs.

Adding -f option forces loading metadata for immediate children in a directory. By default, it loads metadata only at the first time at which a directory is listed.

For example, ls can be used to browse the file system.

./bin/alluxio fs mount /s3/data s3n://data-bucket/
# Loads metadata for all immediate children of /s3/data and lists them.
./bin/alluxio fs ls /s3/data/
#
# Forces loading metadata.
aws s3 cp /tmp/somedata s3n://data-bucket/somedata
./bin/alluxio fs ls -f /s3/data 
#
# Files are not removed from Alluxio if they are removed from the UFS (s3 here) only.
aws s3 rm s3n://data-bucket/somedata
./bin/alluxio fs ls -f /s3/data

ls loads the metadata for immedidate children of a directory.

mkdir

The mkdir command creates a new directory in Alluxio space. It is recursive and will create any nonexistent parent directories. Note that the created directory will not be created in the under storage system until a file in the directory is persisted to the underlying storage. Using mkdir on an invalid or already existing path will fail.

For example, mkdir can be used by an admin to set up the basic folder structures.

./bin/alluxio fs mkdir /users
./bin/alluxio fs mkdir /users/Alice
./bin/alluxio fs mkdir /users/Bob

mount

The mount command links an under storage path to an Alluxio path, and files and folders created in Alluxio space under the path will be backed by a corresponding file or folder in the under storage path. For more details, see Unified Namespace.

For example, mount can be used to make data in another storage system available in Alluxio.

./bin/alluxio fs mount /s3/data s3n://data-bucket/

mv

The mv command moves a file or directory to another path in Alluxio. The destination path must not exist or be a directory. If it is a directory, the file or directory will be placed as a child of the directory. mv is purely a metadata operation and does not affect the data blocks of the file. mv cannot be done between mount points of different under storage systems.

For example, mv can be used to move older data into a non working directory.

./bin/alluxio fs mv /data/2014 /data/archives/2014

persist

The persist command persists data in Alluxio storage into the under storage system. This is a data operation and will take time depending on how large the file is. After persist is complete, the file in Alluxio will be backed by the file in the under storage, make it still valid if the Alluxio blocks are evicted or otherwise lost.

For example, persist can be used after filtering a series of temporary files for the ones containing useful data.

./bin/alluxio fs persist /tmp/experimental-logs-2.txt

pin

The pin command marks a file or folder as pinned in Alluxio. This is a metadata operation and will not cause any data to be loaded into Alluxio. If a file is pinned, any blocks belonging to the file will never be evicted from an Alluxio worker. If there are too many pinned files, Alluxio workers may run low on storage space preventing other files from being cached.

For example, pin can be used to manually ensure performance if the administrator understands the workloads well.

./bin/alluxio fs pin /data/today

report

The report command marks a file as lost to the Alluxio master. This command should only be used with files created using the Lineage API. Marking a file as lost will cause the master to schedule a recomputation job to regenerate the file.

For example, report can be used to force recomputation of a file.

./bin/alluxio fs report /tmp/lineage-file

rm

The rm command removes a file from Alluxio space and the under storage system. The file will be unavailable immediately after this command returns, but the actual data may be deleted a while later.

Add -R option will delete all contents of the directory and then the directory itself.

For example, rm can be used to remove temporary files which are no longer needed.

./bin/alluxio fs rm /tmp/unused-file

setTtl

The setTtl command sets the time-to-live of a file, in milliseconds. Action parameter will indicate the action to perform once the current time is greater than the TTL + creation time of the file. Action delete (default) will delete file from both Alluxio and the under storage system, whereas action free will just free the file from Alluxio.

For example, setTtl with action delete can be used to clean up files the administrator knows are unnecessary after a period of time, or can be used to just remove the contents from Alluxio to make room for more space in Alluxio.

./bin/alluxio fs setTtl -action free /data/good-for-one-day 86400000

tail

The tail command outputs the last 1 kb of data in a file to the console.

For example, tail can be used to verify the output of a job is in the expected format or contains expected values.

./bin/alluxio fs tail /output/part-00000

touch

The touch command creates a 0-byte file. Files created with touch cannot be overwritten and are mostly useful as flags.

For example, touch can be used to create a file signifying the compeletion of analysis on a directory.

./bin/alluxio fs touch /data/yesterday/_DONE_

unmount

The unmount command disassociates an Alluxio path with an under storage directory. Alluxio metadata for the mount point will be removed along with any data blocks, but the under storage system will retain all metadata and data. See Unified Namespace for more dtails.

For example, unmount can be used to remove an under storage system when the users no longer need data from that system.

./bin/alluxio fs unmount /s3/data

unpin

The unpin command unmarks a file or directory in Alluxio as pinned. This is a metadata operation and will not evict or delete any data blocks. Once a file is unpinned, its data blocks can be evicted from the various Alluxio workers containing the block.

For example, unpin can be used when the administrator knows there is a change in the data access pattern.

./bin/alluxio fs unpin /data/yesterday/join-table

unsetTtl

The unsetTtl command will remove the TTL of a file in Alluxio. This is a metadata operation and will not evict or store blocks in Alluxio. The TTL of a file can later be reset with setTtl.

For example, unsetTtl can be used if a regularly managed file requires manual management due to some special case.

./bin/alluxio fs unsetTtl /data/yesterday/data-not-yet-analyzed