org.apache.commons.io

## Class FileSystemUtils

- java.lang.Object
- - org.apache.commons.io.FileSystemUtils

-     public class FileSystemUtils
      extends Object

  General File System utilities.

  This class provides static utility methods for general file system functions not provided via the JDK `File` class.

  The current functions provided are:

  - Get the free space on a drive
  Since:
    1.1
  Version:
    $Id: FileSystemUtils.java 1686747 2015-06-21 18:44:49Z krosenvold $

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `FileSystemUtils()` Instances should NOT be constructed in standard programming.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `static long` | `freeSpace(String path)` Deprecated. Use freeSpaceKb(String) Deprecated from 1.3, may be removed in 2.0
    `static long` | `freeSpaceKb()` Returns the disk size of the volume which holds the working directory.
    `static long` | `freeSpaceKb(long timeout)` Returns the disk size of the volume which holds the working directory.
    `static long` | `freeSpaceKb(String path)` Returns the free space on a drive or volume in kilobytes by invoking the command line.
    `static long` | `freeSpaceKb(String path, long timeout)` Returns the free space on a drive or volume in kilobytes by invoking the command line.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### FileSystemUtils

          public FileSystemUtils()

      Instances should NOT be constructed in standard programming.

  - ### Method Detail

    - #### freeSpace

          @Deprecated
          public static long freeSpace(String path)
                                throws IOException

      Deprecated. Use freeSpaceKb(String) Deprecated from 1.3, may be removed in 2.0
      Returns the free space on a drive or volume by invoking the command line. This method does not normalize the result, and typically returns bytes on Windows, 512 byte units on OS X and kilobytes on Unix. As this is not very useful, this method is deprecated in favour of `freeSpaceKb(String)` which returns a result in kilobytes.

      Note that some OS's are NOT currently supported, including OS/390, OpenVMS.

           FileSystemUtils.freeSpace("C:");       // Windows
           FileSystemUtils.freeSpace("/volume");  // *nix

      The free space is calculated via the command line. It uses 'dir /-c' on Windows and 'df' on *nix.
      Parameters:
        `path` - the path to get free space for, not null, not empty on Unix
      Returns:
        the amount of free drive space on the drive or volume
      Throws:
        `IllegalArgumentException` - if the path is invalid
        `IllegalStateException` - if an error occurred in initialisation
        `IOException` - if an error occurs when finding the free space
      Since:
        1.1, enhanced OS support in 1.2 and 1.3

    - #### freeSpaceKb

          public static long freeSpaceKb(String path)
                                  throws IOException

      Returns the free space on a drive or volume in kilobytes by invoking the command line.

           FileSystemUtils.freeSpaceKb("C:");       // Windows
           FileSystemUtils.freeSpaceKb("/volume");  // *nix

      The free space is calculated via the command line. It uses 'dir /-c' on Windows, 'df -kP' on AIX/HP-UX and 'df -k' on other Unix.

      In order to work, you must be running Windows, or have a implementation of Unix df that supports GNU format when passed -k (or -kP). If you are going to rely on this code, please check that it works on your OS by running some simple tests to compare the command line with the output from this class. If your operating system isn't supported, please raise a JIRA call detailing the exact result from df -k and as much other detail as possible, thanks.

      Parameters:
        `path` - the path to get free space for, not null, not empty on Unix
      Returns:
        the amount of free drive space on the drive or volume in kilobytes
      Throws:
        `IllegalArgumentException` - if the path is invalid
        `IllegalStateException` - if an error occurred in initialisation
        `IOException` - if an error occurs when finding the free space
      Since:
        1.2, enhanced OS support in 1.3

    - #### freeSpaceKb

          public static long freeSpaceKb(String path,
                         long timeout)
                                  throws IOException

      Returns the free space on a drive or volume in kilobytes by invoking the command line.

           FileSystemUtils.freeSpaceKb("C:");       // Windows
           FileSystemUtils.freeSpaceKb("/volume");  // *nix

      The free space is calculated via the command line. It uses 'dir /-c' on Windows, 'df -kP' on AIX/HP-UX and 'df -k' on other Unix.

      In order to work, you must be running Windows, or have a implementation of Unix df that supports GNU format when passed -k (or -kP). If you are going to rely on this code, please check that it works on your OS by running some simple tests to compare the command line with the output from this class. If your operating system isn't supported, please raise a JIRA call detailing the exact result from df -k and as much other detail as possible, thanks.

      Parameters:
        `path` - the path to get free space for, not null, not empty on Unix
        `timeout` - The timeout amount in milliseconds or no timeout if the value is zero or less
      Returns:
        the amount of free drive space on the drive or volume in kilobytes
      Throws:
        `IllegalArgumentException` - if the path is invalid
        `IllegalStateException` - if an error occurred in initialisation
        `IOException` - if an error occurs when finding the free space
      Since:
        2.0

    - #### freeSpaceKb

          public static long freeSpaceKb()
                                  throws IOException

      Returns the disk size of the volume which holds the working directory.

      Identical to:

           freeSpaceKb(new File(".").getAbsolutePath())

      Returns:
        the amount of free drive space on the drive or volume in kilobytes
      Throws:
        `IllegalStateException` - if an error occurred in initialisation
        `IOException` - if an error occurs when finding the free space
      Since:
        2.0

    - #### freeSpaceKb

          public static long freeSpaceKb(long timeout)
                                  throws IOException

      Returns the disk size of the volume which holds the working directory.

      Identical to:

           freeSpaceKb(new File(".").getAbsolutePath())

      Parameters:
        `timeout` - The timeout amount in milliseconds or no timeout if the value is zero or less
      Returns:
        the amount of free drive space on the drive or volume in kilobytes
      Throws:
        `IllegalStateException` - if an error occurred in initialisation
        `IOException` - if an error occurs when finding the free space
      Since:
        2.0

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