Interactive installer

For central installation on a multi-user machine, do the following from an administrator account.

Run the Python interpreter (instructions), and type the commands:

    >>> import nltk
    >>> nltk.download()

A new window should open, showing the NLTK Downloader.  Click on the File menu and select Change Download Directory.  For central installation, set this to C:\nltk_data (Windows), or /usr/share/nltk_data (Mac, Unix).  Next, select the packages or collections you want to download.

If you did not install the data to one of the above central locations, you will need to set the NLTK_DATA environment variable to specify the location of the data.  (On a Windows machine, do right click on "My Computer", select Properties > Advanced > Environment Variables > User Variables > New...)

Test that the data has been installed as follows.  (This assumes you downloaded the Brown Corpus):

    >>> from nltk.corpus import brown
    >>> brown.words()
    ['The', 'Fulton', 'County', 'Grand', 'Jury', 'said', ...]

Command line installation

The downloader will search for an existing nltk_data directory to install NLTK data.  If one does not exist it will attempt to create one in a central location (when using an administrator account) or otherwise in the user's filespace.  If necessary, run the download command from an administrator account, or using sudo.  The default system location on Windows is C:\nltk_data; and on Mac and Unix is /usr/share/nltk_data.  You can use the -d flag to specify a different location (but if you do this, be sure to set the NLTK_DATA environment variable accordingly).

Python 2.5 and 2.6: Run the command "python -m nltk.downloader all".  To ensure central installation, run the command "sudo python -m nltk.downloader -d /usr/share/nltk_data all".

Python 2.4: Locate downloader.py inside Python's site-packages/nltk directory, then run the command "python downloader.py all".  To ensure central installation, run the command "sudo python downloader.py -d /usr/share/nltk_data all".

Windows: Use the "Run..." option on the Start menu.  Windows Vista users need to first turn on this option, using Start -> Properties -> Customize to check the box to activate the "Run..." option. 

Test the installation: Check that the user environment and privileges are set correctly by logging in to a user account,
starting the Python interpreter, and accessing the Brown Corpus (see the previous section).