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, WebHDFS, S3 FS, and others. The FS shell is invoked by:
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.
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.
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](../hadoop-hdfs/HdfsPermissionsGuide.html).
Options
* The -R option will make the change recursively through the directory structure.
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](../hadoop-hdfs/HdfsPermissionsGuide.html).
Options
* The -R option will make the change recursively through the directory structure.
chown
-----
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](../hadoop-hdfs/HdfsPermissionsGuide.html).
Options
* The -R option will make the change recursively through the directory structure.
copyFromLocal
-------------
Usage: `hadoop fs -copyFromLocal <localsrc> URI`
Similar to put command, except that the source is restricted to a local file reference.
Options:
* The -f option will overwrite the destination if it already exists.
copyToLocal
-----------
Usage: `hadoop fs -copyToLocal [-ignorecrc] [-crc] URI <localdst> `
Similar to get command, except that the destination is restricted to a local file reference.
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 -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.
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:
* The -f option will overwrite the destination if it 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, then 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.
* The -s option will result in an aggregate summary of file lengths being displayed, rather than the individual files. Without the -s option, calculation is done by going 1-level deep from the given path.
* The -x option will exclude 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.
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<br/>-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.
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.
* expression -a expression<br/>expression -and expression<br/>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.
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.
Displays the extended attribute names and values (if any) for a file or directory.
Options:
* -R: Recursively list the attributes for all files and directories.
* -n name: Dump the named extended attribute value.
* -d: Dump all extended attribute values associated with pathname.
* -e *encoding*: Encode values after retrieving them. Valid encodings are "text", "hex", and "base64". Values encoded as text strings are enclosed in double quotes ("), and values encoded as hexadecimal and base64 are prefixed with 0x and 0s, respectively.
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.
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.
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.
* 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 file(s) immediately. This can be useful when it is necessary to delete files from an over-quota directory.
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 are added to the ACL, and existing entries are retained.
* -x: Remove specified ACL 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.
Usage: `hadoop fs -setfattr -n name [-v value] | -x name <path> `
Sets an extended attribute name and value for a file or directory.
Options:
* -b: Remove all but the base ACL entries. The entries for user, group and others are retained for compatibility with permission bits.
* -n name: The extended attribute name.
* -v value: The extended attribute value. There are three different encoding methods for the value. If the argument is enclosed in double quotes, then the value is the string inside the quotes. If the argument is prefixed with 0x or 0X, then it is taken as a hexadecimal number. If the argument begins with 0s or 0S, then it is taken as a base64 encoding.
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 the 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] <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:
*`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.
