Class NotebookObject

Start the SAGE Notebook server. 

INPUT:
    directory     -- directory that contains the SAGE notebook files;
                     The default is .sage/sage_notebook, in your home directory.
    port          -- (default: 8000), port to serve the notebook on
    address       -- (default: 'localhost'), address of network interface to listen on;
                     give '' to listen on all interfaces.
    port_tries    -- (default: 0), number of additional ports to try if the
                     first one doesn't work (*not* implemented)
    secure        -- (default: False) if True use https so all
                     communication, e.g., logins and passwords,
                     between web browsers and the SAGE notebook is
                     encrypted (via GNU TLS).  *Highly recommended!*
    require_login -- (default: True) if True login is required else web user is
                     automatically logged in as user admin
    reset         -- (default: False) if True allows you to set the
                     admin password.  Use this if you forget your
                     admin password.
    accounts      -- (default: False) if True, any visitor to the website
                     will be able to create a new account.  If False,
                     only the admin can create accounts (currently, this
                     can only be done by running with accounts=True for
                     a few minutes, or on the command line with, e.g., 
                         nb = load('./sage/sage_notebook/nb.sobj')
                         nb.set_accounts(True)
                         nb.add_user("username", "password", "email@place", "user")
                         nb.save()
    open_viewer   -- (default: True) whether to pop up a web browser.
                     You can override the default browser by setting
                     the SAGE_BROWSER environment variable, e.g., by putting
                         export SAGE_BROWSER="firefox"
                     in the file .bashrc in your home directory.
    timeout       -- (default: 0) seconds until idle worksheet sessions
                     automatically timeout, i.e., the corresponding
                     Sage session terminates.  0 means 'never timeout'.
    server_pool   -- list;   The server_pool option specifies that worksheet processes run
                     as a separate user (chosen from the list in the server_pool -- see below). 
                  
\begin{verbatim}

NOTE: If you have problems with the server certificate hostname not
matching, do \code{notebook.setup()}.

EXAMPLES:

1. I just want to run the SAGE notebook.  Type

         notebook()

2. I want to run the SAGE notebook server on a remote machine
   and be the only person allowed to log in.  Type

     notebook(address='', secure=True)

   the first time you do this you'll be prompted to set
   an administrator password.  Use this to login.
   NOTE: You may have to run notebook.setup() again and change
   the hostname.

3. I just want to run the server locally on my laptop at a coffee
   shop with no wifi and do not want to be bothered with having to log in,
   and I am *absolutely certain* I am the only
   user logged into my laptop so I do not have to worry about
   somebody else using the notebook on localhost and deleting my
   files.  Use

              notebook(require_login=False)

4. I want to create a SAGE notebook server that is open to anybody
   in the world to create new accounts, etc.  To run the SAGE
   notebook publically (1) at a minimu run it from a chroot jail
   (see the SAGE install guide), and (2) use a command like

     notebook(address='', server_pool=['sage1@localhost'], ulimit='-v 500000', accounts=True)

   The server_pool option specifies that worksheet processes run
   as a separate user.  The ulimit option restricts the memory
   available to each worksheet processes to 500MB.  See help on
   the accounts option above.

   Be sure to make that the sage_notebook/nb.sobj and contents
   of sage_notebook/backups is chmod og-rwx, i.e., only readable
   by the notebook process, since otherwise any user can read
   nb.sobj, which contains user email addresses and account
   information (password are stored hashed, so less worries there). 


INPUT:  (more advanced)

NOTE: The values of these two properties default to what they were
last time the notebook command was called.

    server_pool -- (default: None), if given, should be a list like 
                   ['sage1@localhost', 'sage2@localhost'], where
                   you have setup ssh keys so that typing
                       ssh sage1@localhost
                   logs in without requiring a password, e.g., by typing
                   as the notebook server user
                       cd; ssh-keygen -t rsa
                   then put ~/.ssh/id_rsa.pub as the file .ssh/authorized_keys2.
                   Note -- you have to get the permissions of files
                   and directories just right -- do a web search
                   for more details.
                  
    ulimit      -- (default: None -- leave as is), if given and server_pool is also given,
                   the worksheet processes are run with these constraints.
                   See the ulimit documentation. Common options include:
                       -f   The maximum size of files created by the shell
                       -t   The maximum amount of cpu time in seconds. 
                       -u   The maximum number of processes available to a single user. 
                       -v   The maximum amount of virtual memory available to the process.
                   Values are in 1024-byte increments, except for `-t', which is in seconds.
                   Example:  ulimit="-v 400000 -t 30"

\end{verbatim}