SWI-Prolog 7.4.2 Reference Manual: Section A.17

## A.17 library(www_browser): Activating your Web-browser

This library deals with the very system-dependent task of opening a web page in a browser. See also `library(url)` and the HTTP package.

www_open_url(+URL)
  Open URL in an external web browser. The reason to place this in the library is to centralise the maintenance on this highly platform- and browser-specific task. It distinguishes between the following cases:

  - MS-Windows
    If it detects MS-Windows it uses win_shell/2 to open the URL. The behaviour and browser started depends on the version of Windows and Windows-shell configuration, but in general it should be the behaviour expected by the user.

  - Other platforms
    On other platforms it tests the environment variable (see getenv/2) named `BROWSER` or uses netscape if this variable is not set. If the browser is either `mozilla` or `netscape`, www_open_url/1 first tries to open a new window on a running browser using the `-remote` option of Netscape. If this fails or the browser is not `mozilla` or `netscape` the system simply passes the URL as first argument to the program.