20.1. "webbrowser" — Convenient Web-browser controller
******************************************************

**Source code:** Lib/webbrowser.py

======================================================================

The "webbrowser" module provides a high-level interface to allow
displaying Web-based documents to users. Under most circumstances,
simply calling the "open()" function from this module will do the
right thing.

Under Unix, graphical browsers are preferred under X11, but text-mode
browsers will be used if graphical browsers are not available or an
X11 display isn’t available.  If text-mode browsers are used, the
calling process will block until the user exits the browser.

If the environment variable "BROWSER" exists, it is interpreted to
override the platform default list of browsers, as an
"os.pathsep"-separated list of browsers to try in order.  When the
value of a list part contains the string "%s", then it is  interpreted
as a literal browser command line to be used with the argument URL
substituted for "%s"; if the part does not contain "%s", it is simply
interpreted as the name of the browser to launch. [1]

For non-Unix platforms, or when a remote browser is available on Unix,
the controlling process will not wait for the user to finish with the
browser, but allow the remote browser to maintain its own windows on
the display.  If remote browsers are not available on Unix, the
controlling process will launch a new browser and wait.

The script **webbrowser** can be used as a command-line interface for
the module. It accepts a URL as the argument. It accepts the following
optional parameters: "-n" opens the URL in a new browser window, if
possible; "-t" opens the URL in a new browser page (“tab”). The
options are, naturally, mutually exclusive.  Usage example:

   python -m webbrowser -t "http://www.python.org"

The following exception is defined:

exception webbrowser.Error

   Exception raised when a browser control error occurs.

The following functions are defined:

webbrowser.open(url, new=0, autoraise=True)

   Display *url* using the default browser. If *new* is 0, the *url*
   is opened in the same browser window if possible.  If *new* is 1, a
   new browser window is opened if possible.  If *new* is 2, a new
   browser page (“tab”) is opened if possible.  If *autoraise* is
   "True", the window is raised if possible (note that under many
   window managers this will occur regardless of the setting of this
   variable).

   Note that on some platforms, trying to open a filename using this
   function, may work and start the operating system’s associated
   program.  However, this is neither supported nor portable.

   Changed in version 2.5: *new* can now be 2.

webbrowser.open_new(url)

   Open *url* in a new window of the default browser, if possible,
   otherwise, open *url* in the only browser window.

webbrowser.open_new_tab(url)

   Open *url* in a new page (“tab”) of the default browser, if
   possible, otherwise equivalent to "open_new()".

   New in version 2.5.

webbrowser.get([name])

   Return a controller object for the browser type *name*.  If *name*
   is empty, return a controller for a default browser appropriate to
   the caller’s environment.

webbrowser.register(name, constructor[, instance])

   Register the browser type *name*.  Once a browser type is
   registered, the "get()" function can return a controller for that
   browser type.  If *instance* is not provided, or is "None",
   *constructor* will be called without parameters to create an
   instance when needed.  If *instance* is provided, *constructor*
   will never be called, and may be "None".

   This entry point is only useful if you plan to either set the
   "BROWSER" variable or call "get()" with a nonempty argument
   matching the name of a handler you declare.

A number of browser types are predefined.  This table gives the type
names that may be passed to the "get()" function and the corresponding
instantiations for the controller classes, all defined in this module.

+-------------------------+-------------------------------------------+---------+
| Type Name               | Class Name                                | Notes   |
+=========================+===========================================+=========+
| "'mozilla'"             | "Mozilla('mozilla')"                      |         |
+-------------------------+-------------------------------------------+---------+
| "'firefox'"             | "Mozilla('mozilla')"                      |         |
+-------------------------+-------------------------------------------+---------+
| "'netscape'"            | "Mozilla('netscape')"                     |         |
+-------------------------+-------------------------------------------+---------+
| "'galeon'"              | "Galeon('galeon')"                        |         |
+-------------------------+-------------------------------------------+---------+
| "'epiphany'"            | "Galeon('epiphany')"                      |         |
+-------------------------+-------------------------------------------+---------+
| "'skipstone'"           | "BackgroundBrowser('skipstone')"          |         |
+-------------------------+-------------------------------------------+---------+
| "'kfmclient'"           | "Konqueror()"                             | (1)     |
+-------------------------+-------------------------------------------+---------+
| "'konqueror'"           | "Konqueror()"                             | (1)     |
+-------------------------+-------------------------------------------+---------+
| "'kfm'"                 | "Konqueror()"                             | (1)     |
+-------------------------+-------------------------------------------+---------+
| "'mosaic'"              | "BackgroundBrowser('mosaic')"             |         |
+-------------------------+-------------------------------------------+---------+
| "'opera'"               | "Opera()"                                 |         |
+-------------------------+-------------------------------------------+---------+
| "'grail'"               | "Grail()"                                 |         |
+-------------------------+-------------------------------------------+---------+
| "'links'"               | "GenericBrowser('links')"                 |         |
+-------------------------+-------------------------------------------+---------+
| "'elinks'"              | "Elinks('elinks')"                        |         |
+-------------------------+-------------------------------------------+---------+
| "'lynx'"                | "GenericBrowser('lynx')"                  |         |
+-------------------------+-------------------------------------------+---------+
| "'w3m'"                 | "GenericBrowser('w3m')"                   |         |
+-------------------------+-------------------------------------------+---------+
| "'windows-default'"     | "WindowsDefault"                          | (2)     |
+-------------------------+-------------------------------------------+---------+
| "'macosx'"              | "MacOSX('default')"                       | (3)     |
+-------------------------+-------------------------------------------+---------+
| "'safari'"              | "MacOSX('safari')"                        | (3)     |
+-------------------------+-------------------------------------------+---------+
| "'google-chrome'"       | "Chrome('google-chrome')"                 | (4)     |
+-------------------------+-------------------------------------------+---------+
| "'chrome'"              | "Chrome('chrome')"                        | (4)     |
+-------------------------+-------------------------------------------+---------+
| "'chromium'"            | "Chromium('chromium')"                    | (4)     |
+-------------------------+-------------------------------------------+---------+
| "'chromium-browser'"    | "Chromium('chromium-browser')"            | (4)     |
+-------------------------+-------------------------------------------+---------+

Notes:

1. “Konqueror” is the file manager for the KDE desktop environment
   for Unix, and only makes sense to use if KDE is running.  Some way
   of reliably detecting KDE would be nice; the "KDEDIR" variable is
   not sufficient.  Note also that the name “kfm” is used even when
   using the **konqueror** command with KDE 2 — the implementation
   selects the best strategy for running Konqueror.

2. Only on Windows platforms.

3. Only on Mac OS X platform.

4. Support for Chrome/Chromium has been added in version 2.7.5.

Here are some simple examples:

   url = 'http://www.python.org/'

   # Open URL in a new tab, if a browser window is already open.
   webbrowser.open_new_tab(url + 'doc/')

   # Open URL in new window, raising the window if possible.
   webbrowser.open_new(url)


20.1.1. Browser Controller Objects
==================================

Browser controllers provide these methods which parallel three of the
module-level convenience functions:

controller.open(url, new=0, autoraise=True)

   Display *url* using the browser handled by this controller. If
   *new* is 1, a new browser window is opened if possible. If *new* is
   2, a new browser page (“tab”) is opened if possible.

controller.open_new(url)

   Open *url* in a new window of the browser handled by this
   controller, if possible, otherwise, open *url* in the only browser
   window.  Alias "open_new()".

controller.open_new_tab(url)

   Open *url* in a new page (“tab”) of the browser handled by this
   controller, if possible, otherwise equivalent to "open_new()".

   New in version 2.5.

-[ Footnotes ]-

[1] Executables named here without a full path will be searched in
    the directories given in the "PATH" environment variable.
