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Showing content from https://hadoop.apache.org/docs/r1.2.1/api/org/apache/hadoop/fs/FileSystem.html below:

FileSystem (Hadoop 1.2.1 API)

java.lang.Object
  org.apache.hadoop.conf.Configured
      org.apache.hadoop.fs.FileSystem

All Implemented Interfaces:

Closeable, Configurable

Direct Known Subclasses:

FilterFileSystem, FTPFileSystem, KosmosFileSystem, NativeS3FileSystem, RawLocalFileSystem, S3FileSystem

public abstract class FileSystem
extends Configured
implements Closeable

An abstract base class for a fairly generic filesystem. It may be implemented as a distributed filesystem, or as a "local" one that reflects the locally-connected disk. The local version exists for small Hadoop instances and for testing.

All user code that may potentially use the Hadoop Distributed File System should be written to use a FileSystem object. The Hadoop DFS is a multi-machine system that appears as a single disk. It's useful because of its fault tolerance and potentially very large capacity.

The local implementation is LocalFileSystem and distributed implementation is DistributedFileSystem.

public static final String FS_DEFAULT_NAME_KEY

See Also:

Constant Field Values

public static final org.apache.commons.logging.Log LOG

protected FileSystem.Statistics statistics

The statistics for this file system.

protected FileSystem()

public static void addFileSystemForTesting(URI uri,
                                           Configuration conf,
                                           FileSystem fs)
                                    throws IOException

This method adds a file system for testing so that we can find it later. It is only for testing.

Parameters:

uri - the uri to store it under

conf - the configuration to store it under

fs - the file system to store

Throws:

IOException

public static FileSystem get(URI uri,
                             Configuration conf,
                             String user)
                      throws IOException,
                             InterruptedException

Throws:

IOException

InterruptedException

public static FileSystem get(Configuration conf)
                      throws IOException

Returns the configured filesystem implementation.

Throws:

IOException

public static URI getDefaultUri(Configuration conf)

Get the default filesystem URI from a configuration.

Parameters:

conf - the configuration to access

Returns:

the uri of the default filesystem

public static void setDefaultUri(Configuration conf,
                                 URI uri)

Set the default filesystem URI in a configuration.

Parameters:

conf - the configuration to alter

uri - the new default filesystem uri

public static void setDefaultUri(Configuration conf,
                                 String uri)

Set the default filesystem URI in a configuration.

Parameters:

conf - the configuration to alter

uri - the new default filesystem uri

@InterfaceAudience.Private
public static int getCacheSize()

Get the number of entries in the filesystem cache

Returns:

the number of entries in the filesystem cache

public void initialize(URI name,
                       Configuration conf)
                throws IOException

Called after a new FileSystem instance is constructed.

Parameters:

name - a uri whose authority section names the host, port, etc. for this FileSystem

conf - the configuration

Throws:

IOException

public abstract URI getUri()

Returns a URI whose scheme and authority identify this FileSystem.

protected URI getCanonicalUri()

Resolve the uri's hostname and add the default port if not in the uri

Returns:

URI

See Also:

NetUtils.getCanonicalUri(URI, int)

protected int getDefaultPort()

Get the default port for this file system.

Returns:

the default port or 0 if there isn't one

public String getCanonicalServiceName()

Get a canonical service name for this file system. The token cache is the only user of this value, and uses it to lookup this filesystem's service tokens. The token cache will not attempt to acquire tokens if the service is null.

Returns:

a service string that uniquely identifies this file system, null if the filesystem does not implement tokens

See Also:

SecurityUtil.buildDTServiceName(URI, int)

public String getName()

Deprecated. call #getUri() instead.

public static FileSystem getNamed(String name,
                                  Configuration conf)
                           throws IOException

Deprecated. call #get(URI,Configuration) instead.

Throws:

IOException

public static LocalFileSystem getLocal(Configuration conf)
                                throws IOException

Get the local file syste

Parameters:

conf - the configuration to configure the file system with

Returns:

a LocalFileSystem

Throws:

IOException

public static FileSystem get(URI uri,
                             Configuration conf)
                      throws IOException

Returns the FileSystem for this URI's scheme and authority. The scheme of the URI determines a configuration property name, fs.scheme.class whose value names the FileSystem class. The entire URI is passed to the FileSystem instance's initialize method.

Throws:

IOException

public static void closeAll()
                     throws IOException

Close all cached filesystems. Be sure those filesystems are not used anymore.

Throws:

IOException

public static void closeAllForUGI(UserGroupInformation ugi)
                           throws IOException

Close all cached filesystems for a given UGI. Be sure those filesystems are not used anymore.

Parameters:

ugi -

Throws:

IOException

public Path makeQualified(Path path)

Make sure that a path specifies a FileSystem.

public static FSDataOutputStream create(FileSystem fs,
                                        Path file,
                                        FsPermission permission)
                                 throws IOException

create a file with the provided permission The permission of the file is set to be the provided permission as in setPermission, not permission&~umask It is implemented using two RPCs. It is understood that it is inefficient, but the implementation is thread-safe. The other option is to change the value of umask in configuration to be 0, but it is not thread-safe.

Parameters:

fs - file system handle

file - the name of the file to be created

permission - the permission of the file

Returns:

an output stream

Throws:

IOException

public static boolean mkdirs(FileSystem fs,
                             Path dir,
                             FsPermission permission)
                      throws IOException

create a directory with the provided permission The permission of the directory is set to be the provided permission as in setPermission, not permission&~umask

Parameters:

fs - file system handle

dir - the name of the directory to be created

permission - the permission of the directory

Returns:

true if the directory creation succeeds; false otherwise

Throws:

IOException

See Also:

create(FileSystem, Path, FsPermission)

protected void checkPath(Path path)

Check that a Path belongs to this FileSystem.

public BlockLocation[] getFileBlockLocations(FileStatus file,
                                             long start,
                                             long len)
                                      throws IOException

Return an array containing hostnames, offset and size of portions of the given file. For a nonexistent file or regions, null will be returned. This call is most helpful with DFS, where it returns hostnames of machines that contain the given file. The FileSystem will simply return an elt containing 'localhost'.

Throws:

IOException

public abstract FSDataInputStream open(Path f,
                                       int bufferSize)
                                throws IOException

Opens an FSDataInputStream at the indicated Path.

Parameters:

f - the file name to open

bufferSize - the size of the buffer to be used.

Throws:

IOException

public FSDataInputStream open(Path f)
                       throws IOException

Opens an FSDataInputStream at the indicated Path.

Parameters:

f - the file to open

Throws:

IOException

public FSDataOutputStream create(Path f)
                          throws IOException

Opens an FSDataOutputStream at the indicated Path. Files are overwritten by default.

Throws:

IOException

public FSDataOutputStream create(Path f,
                                 boolean overwrite)
                          throws IOException

Opens an FSDataOutputStream at the indicated Path.

Throws:

IOException

public FSDataOutputStream create(Path f,
                                 Progressable progress)
                          throws IOException

Create an FSDataOutputStream at the indicated Path with write-progress reporting. Files are overwritten by default.

Throws:

IOException

public FSDataOutputStream create(Path f,
                                 short replication)
                          throws IOException

Opens an FSDataOutputStream at the indicated Path. Files are overwritten by default.

Throws:

IOException

public FSDataOutputStream create(Path f,
                                 short replication,
                                 Progressable progress)
                          throws IOException

Opens an FSDataOutputStream at the indicated Path with write-progress reporting. Files are overwritten by default.

Throws:

IOException

public FSDataOutputStream create(Path f,
                                 boolean overwrite,
                                 int bufferSize)
                          throws IOException

Opens an FSDataOutputStream at the indicated Path.

Parameters:

f - the file name to open

overwrite - if a file with this name already exists, then if true, the file will be overwritten, and if false an error will be thrown.

bufferSize - the size of the buffer to be used.

Throws:

IOException

public FSDataOutputStream create(Path f,
                                 boolean overwrite,
                                 int bufferSize,
                                 Progressable progress)
                          throws IOException

Opens an FSDataOutputStream at the indicated Path with write-progress reporting.

Parameters:

f - the file name to open

overwrite - if a file with this name already exists, then if true, the file will be overwritten, and if false an error will be thrown.

bufferSize - the size of the buffer to be used.

Throws:

IOException

public FSDataOutputStream create(Path f,
                                 boolean overwrite,
                                 int bufferSize,
                                 short replication,
                                 long blockSize)
                          throws IOException

Opens an FSDataOutputStream at the indicated Path.

Parameters:

f - the file name to open

overwrite - if a file with this name already exists, then if true, the file will be overwritten, and if false an error will be thrown.

bufferSize - the size of the buffer to be used.

replication - required block replication for the file.

Throws:

IOException

public FSDataOutputStream create(Path f,
                                 boolean overwrite,
                                 int bufferSize,
                                 short replication,
                                 long blockSize,
                                 Progressable progress)
                          throws IOException

Opens an FSDataOutputStream at the indicated Path with write-progress reporting.

Parameters:

f - the file name to open

overwrite - if a file with this name already exists, then if true, the file will be overwritten, and if false an error will be thrown.

bufferSize - the size of the buffer to be used.

replication - required block replication for the file.

Throws:

IOException

public abstract FSDataOutputStream create(Path f,
                                          FsPermission permission,
                                          boolean overwrite,
                                          int bufferSize,
                                          short replication,
                                          long blockSize,
                                          Progressable progress)
                                   throws IOException

Opens an FSDataOutputStream at the indicated Path with write-progress reporting.

Parameters:

f - the file name to open

permission -

overwrite - if a file with this name already exists, then if true, the file will be overwritten, and if false an error will be thrown.

bufferSize - the size of the buffer to be used.

replication - required block replication for the file.

blockSize -

progress -

Throws:

IOException

See Also:

setPermission(Path, FsPermission)

@Deprecated
public FSDataOutputStream createNonRecursive(Path f,
                                                        boolean overwrite,
                                                        int bufferSize,
                                                        short replication,
                                                        long blockSize,
                                                        Progressable progress)
                                      throws IOException

Deprecated. API only for 0.20-append

Opens an FSDataOutputStream at the indicated Path with write-progress reporting. Same as create(), except fails if parent directory doesn't already exist.

Parameters:

f - the file name to open

overwrite - if a file with this name already exists, then if true, the file will be overwritten, and if false an error will be thrown.

bufferSize - the size of the buffer to be used.

replication - required block replication for the file.

blockSize -

progress -

Throws:

IOException

See Also:

setPermission(Path, FsPermission)

@Deprecated
public FSDataOutputStream createNonRecursive(Path f,
                                                        FsPermission permission,
                                                        boolean overwrite,
                                                        int bufferSize,
                                                        short replication,
                                                        long blockSize,
                                                        Progressable progress)
                                      throws IOException

Deprecated. API only for 0.20-append

Opens an FSDataOutputStream at the indicated Path with write-progress reporting. Same as create(), except fails if parent directory doesn't already exist.

Parameters:

f - the file name to open

permission -

overwrite - if a file with this name already exists, then if true, the file will be overwritten, and if false an error will be thrown.

bufferSize - the size of the buffer to be used.

replication - required block replication for the file.

blockSize -

progress -

Throws:

IOException

See Also:

setPermission(Path, FsPermission)

public boolean createNewFile(Path f)
                      throws IOException

Creates the given Path as a brand-new zero-length file. If create fails, or if it already existed, return false.

Throws:

IOException

public FSDataOutputStream append(Path f)
                          throws IOException

Append to an existing file (optional operation). Same as append(f, getConf().getInt("io.file.buffer.size", 4096), null)

Parameters:

f - the existing file to be appended.

Throws:

IOException

public FSDataOutputStream append(Path f,
                                 int bufferSize)
                          throws IOException

Append to an existing file (optional operation). Same as append(f, bufferSize, null).

Parameters:

f - the existing file to be appended.

bufferSize - the size of the buffer to be used.

Throws:

IOException

public abstract FSDataOutputStream append(Path f,
                                          int bufferSize,
                                          Progressable progress)
                                   throws IOException

Append to an existing file (optional operation).

Parameters:

f - the existing file to be appended.

bufferSize - the size of the buffer to be used.

progress - for reporting progress if it is not null.

Throws:

IOException

public void concat(Path trg,
                   Path[] srcs)
            throws IOException

Concat existing files together.

Parameters:

trg - the path to the target destination.

psrcs - the paths to the sources to use for the concatenation.

Throws:

IOException

@Deprecated
public short getReplication(Path src)
                     throws IOException

Deprecated. Use getFileStatus() instead

Get replication.

Parameters:

src - file name

Returns:

file replication

Throws:

IOException

public boolean setReplication(Path src,
                              short replication)
                       throws IOException

Set replication for an existing file.

Parameters:

src - file name

replication - new replication

Returns:

true if successful; false if file does not exist or is a directory

Throws:

IOException

public abstract boolean rename(Path src,
                               Path dst)
                        throws IOException

Renames Path src to Path dst. Can take place on local fs or remote DFS.

Throws:

IOException

@Deprecated
public abstract boolean delete(Path f)
                        throws IOException

Deprecated. Use delete(Path, boolean) instead

Throws:

IOException

public abstract boolean delete(Path f,
                               boolean recursive)
                        throws IOException

Delete a file.

Parameters:

f - the path to delete.

recursive - if path is a directory and set to true, the directory is deleted else throws an exception. In case of a file the recursive can be set to either true or false.

Returns:

true if delete is successful else false.

Throws:

IOException

public boolean deleteOnExit(Path f)
                     throws IOException

Mark a path to be deleted when FileSystem is closed. When the JVM shuts down, all FileSystem objects will be closed automatically. Then, the marked path will be deleted as a result of closing the FileSystem. The path has to exist in the file system.

Parameters:

f - the path to delete.

Returns:

true if deleteOnExit is successful, otherwise false.

Throws:

IOException

protected void processDeleteOnExit()

Delete all files that were marked as delete-on-exit. This recursively deletes all files in the specified paths.

public boolean exists(Path f)
               throws IOException

Check if exists.

Parameters:

f - source file

Throws:

IOException

@Deprecated
public boolean isDirectory(Path f)
                    throws IOException

Deprecated. Use getFileStatus() instead

Throws:

IOException

public boolean isFile(Path f)
               throws IOException

True iff the named path is a regular file.

Throws:

IOException

@Deprecated
public long getLength(Path f)
               throws IOException

Deprecated. Use getFileStatus() instead

Throws:

IOException

public ContentSummary getContentSummary(Path f)
                                 throws IOException

Return the ContentSummary of a given Path.

Throws:

IOException

public abstract FileStatus[] listStatus(Path f)
                                 throws IOException

List the statuses of the files/directories in the given path if the path is a directory.

Parameters:

f - given path

Returns:

the statuses of the files/directories in the given patch returns null, if Path f does not exist in the FileSystem

Throws:

IOException

public FileStatus[] listStatus(Path f,
                               PathFilter filter)
                        throws IOException

Filter files/directories in the given path using the user-supplied path filter.

Parameters:

f - a path name

filter - the user-supplied path filter

Returns:

an array of FileStatus objects for the files under the given path after applying the filter

Throws:

IOException - if encounter any problem while fetching the status

public FileStatus[] listStatus(Path[] files)
                        throws IOException

Filter files/directories in the given list of paths using default path filter.

Parameters:

files - a list of paths

Returns:

a list of statuses for the files under the given paths after applying the filter default Path filter

Throws:

IOException

public FileStatus[] listStatus(Path[] files,
                               PathFilter filter)
                        throws IOException

Filter files/directories in the given list of paths using user-supplied path filter.

Parameters:

files - a list of paths

filter - the user-supplied path filter

Returns:

a list of statuses for the files under the given paths after applying the filter

Throws:

IOException

public FileStatus[] globStatus(Path pathPattern)
                        throws IOException

Return all the files that match filePattern and are not checksum files. Results are sorted by their names.

A filename pattern is composed of regular characters and special pattern matching characters, which are:

?

Matches any single character.

*

Matches zero or more characters.

[abc]

Matches a single character from character set {a,b,c}.

[a-b]

Matches a single character from the character range {a...b}. Note that character a must be lexicographically less than or equal to character b.

[^a]

Matches a single character that is not from character set or range {a}. Note that the ^ character must occur immediately to the right of the opening bracket.

\c

Removes (escapes) any special meaning of character c.

{ab,cd}

Matches a string from the string set {ab, cd}

{ab,c{de,fh}}

Matches a string from the string set {ab, cde, cfh}

Parameters:

pathPattern - a regular expression specifying a pth pattern

Returns:

an array of paths that match the path pattern

Throws:

IOException

public FileStatus[] globStatus(Path pathPattern,
                               PathFilter filter)
                        throws IOException

Return an array of FileStatus objects whose path names match pathPattern and is accepted by the user-supplied path filter. Results are sorted by their path names. Return null if pathPattern has no glob and the path does not exist. Return an empty array if pathPattern has a glob and no path matches it.

Parameters:

pathPattern - a regular expression specifying the path pattern

filter - a user-supplied path filter

Returns:

an array of FileStatus objects

Throws:

IOException - if any I/O error occurs when fetching file status

public Path getHomeDirectory()

Return the current user's home directory in this filesystem. The default implementation returns "/user/$USER/".

public Token<?> getDelegationToken(String renewer)
                            throws IOException

Get a new delegation token for this file system.

Parameters:

renewer - the account name that is allowed to renew the token.

Returns:

a new delegation token

Throws:

IOException

public abstract void setWorkingDirectory(Path new_dir)

Set the current working directory for the given file system. All relative paths will be resolved relative to it.

Parameters:

new_dir -

public abstract Path getWorkingDirectory()

Get the current working directory for the given file system

Returns:

the directory pathname

public boolean mkdirs(Path f)
               throws IOException

Call mkdirs(Path, FsPermission) with default permission.

Throws:

IOException

public abstract boolean mkdirs(Path f,
                               FsPermission permission)
                        throws IOException

Make the given file and all non-existent parents into directories. Has the semantics of Unix 'mkdir -p'. Existence of the directory hierarchy is not an error.

Throws:

IOException

public void copyFromLocalFile(Path src,
                              Path dst)
                       throws IOException

The src file is on the local disk. Add it to FS at the given dst name and the source is kept intact afterwards

Throws:

IOException

public void moveFromLocalFile(Path[] srcs,
                              Path dst)
                       throws IOException

The src files is on the local disk. Add it to FS at the given dst name, removing the source afterwards.

Throws:

IOException

public void moveFromLocalFile(Path src,
                              Path dst)
                       throws IOException

The src file is on the local disk. Add it to FS at the given dst name, removing the source afterwards.

Throws:

IOException

public void copyFromLocalFile(boolean delSrc,
                              Path src,
                              Path dst)
                       throws IOException

The src file is on the local disk. Add it to FS at the given dst name. delSrc indicates if the source should be removed

Throws:

IOException

public void copyFromLocalFile(boolean delSrc,
                              boolean overwrite,
                              Path[] srcs,
                              Path dst)
                       throws IOException

The src files are on the local disk. Add it to FS at the given dst name. delSrc indicates if the source should be removed

Throws:

IOException

public void copyFromLocalFile(boolean delSrc,
                              boolean overwrite,
                              Path src,
                              Path dst)
                       throws IOException

The src file is on the local disk. Add it to FS at the given dst name. delSrc indicates if the source should be removed

Throws:

IOException

public void copyToLocalFile(Path src,
                            Path dst)
                     throws IOException

The src file is under FS, and the dst is on the local disk. Copy it from FS control to the local dst name.

Throws:

IOException

public void moveToLocalFile(Path src,
                            Path dst)
                     throws IOException

The src file is under FS, and the dst is on the local disk. Copy it from FS control to the local dst name. Remove the source afterwards

Throws:

IOException

public void copyToLocalFile(boolean delSrc,
                            Path src,
                            Path dst)
                     throws IOException

The src file is under FS, and the dst is on the local disk. Copy it from FS control to the local dst name. delSrc indicates if the src will be removed or not.

Throws:

IOException

public Path startLocalOutput(Path fsOutputFile,
                             Path tmpLocalFile)
                      throws IOException

Returns a local File that the user can write output to. The caller provides both the eventual FS target name and the local working file. If the FS is local, we write directly into the target. If the FS is remote, we write into the tmp local area.

Throws:

IOException

public void completeLocalOutput(Path fsOutputFile,
                                Path tmpLocalFile)
                         throws IOException

Called when we're all done writing to the target. A local FS will do nothing, because we've written to exactly the right place. A remote FS will copy the contents of tmpLocalFile to the correct target at fsOutputFile.

Throws:

IOException

public void close()
           throws IOException

No more filesystem operations are needed. Will release any held locks.

Specified by:

close in interface Closeable

Throws:

IOException

public long getUsed()
             throws IOException

Return the total size of all files in the filesystem.

Throws:

IOException

@Deprecated
public long getBlockSize(Path f)
                  throws IOException

Deprecated. Use getFileStatus() instead

Throws:

IOException

@Deprecated
public long getDefaultBlockSize()

Deprecated. use getDefaultBlockSize(Path) instead

Return the number of bytes that large input files should be optimally be split into to minimize i/o time.

public long getDefaultBlockSize(Path f)

Return the number of bytes that large input files should be optimally be split into to minimize i/o time.

Parameters:

f - path of file

Returns:

the default block size for the path's filesystem

@Deprecated
public short getDefaultReplication()

Deprecated. use getDefaultReplication(Path) instead

Get the default replication.

public short getDefaultReplication(Path path)

Get the default replication.

Parameters:

path - of the file

Returns:

default replication for the path's filesystem

public abstract FileStatus getFileStatus(Path f)
                                  throws IOException

Return a file status object that represents the path.

Parameters:

f - The path we want information from

Returns:

a FileStatus object

Throws:

FileNotFoundException - when the path does not exist; IOException see specific implementation

IOException

public FileChecksum getFileChecksum(Path f)
                             throws IOException

Get the checksum of a file.

Parameters:

f - The file path

Returns:

The file checksum. The default return value is null, which indicates that no checksum algorithm is implemented in the corresponding FileSystem.

Throws:

IOException

public void setVerifyChecksum(boolean verifyChecksum)

Set the verify checksum flag. This is only applicable if the corresponding FileSystem supports checksum. By default doesn't do anything.

Parameters:

verifyChecksum -

public void setPermission(Path p,
                          FsPermission permission)
                   throws IOException

Set permission of a path.

Parameters:

p -

permission -

Throws:

IOException

public void setOwner(Path p,
                     String username,
                     String groupname)
              throws IOException

Set owner of a path (i.e. a file or a directory). The parameters username and groupname cannot both be null.

Parameters:

p - The path

username - If it is null, the original username remains unchanged.

groupname - If it is null, the original groupname remains unchanged.

Throws:

IOException

public void setTimes(Path p,
                     long mtime,
                     long atime)
              throws IOException

Set access time of a file

Parameters:

p - The path

mtime - Set the modification time of this file. The number of milliseconds since Jan 1, 1970. A value of -1 means that this call should not set modification time.

atime - Set the access time of this file. The number of milliseconds since Jan 1, 1970. A value of -1 means that this call should not set access time.

Throws:

IOException

public static Map<String,FileSystem.Statistics> getStatistics()

Deprecated. use getAllStatistics() instead

Get the Map of Statistics object indexed by URI Scheme.

Returns:

a Map having a key as URI scheme and value as Statistics object

public static List<FileSystem.Statistics> getAllStatistics()

Return the FileSystem classes that have Statistics

public static FileSystem.Statistics getStatistics(String scheme,
                                                  Class<? extends FileSystem> cls)

Get the statistics for a particular file system

Parameters:

cls - the class to lookup

Returns:

a statistics object

public static void clearStatistics()

public static void printStatistics()
                            throws IOException

Throws:

IOException

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