On this page:
send-url
send-url/ file
send-url/ contents
external-browser
browser-preference?
unix-browser-list
Version: 4.2.1

4 Send URL: Opening a Web Browser

Provides send-url for opening a URL in the user’s chosen web browser.

See also browser/external, which requires scheme/gui, but can prompt the user for a browser if no browser preference is set.

(send-url str    
  [separate-window?    
  #:escape escape?])  void?
  str : string?
  separate-window? : any/c = #t
  escape? : any/c = #t
Opens str, which represents a URL, in a platform-specific manner. For some platforms and configurations, the separate-window? parameter determines if the browser creates a new window to display the URL or not.

Under Windows, send-url normally uses shell-execute to launch a browser. (If the URL appears to contain a fragment, it may use an intermediate redirecting file due to a bug in IE7.)

Under Mac OS X, send-url runs osascript to start the user’s chosen browser.

Under Unix, send-url uses the value of the external-browser parameter to select a browser.

The url string is usually escaped to avoid dangerous shell characters (quotations, dollar signs, backslashes, and non-ASCII). Note that it is a good idea to encode URLs before passing them to this function. Also note that the encoding is meant to make the URL work in shell quotes: URLs can still hold characters like #, ?, and &, so the external-browser should use quotations.

(send-url/file path    
  [separate-window?    
  #:fragment fragment    
  #:query query])  void?
  path : path-string?
  separate-window? : any/c = #t
  fragment : (or/c string? false/c) = #f
  query : (or/c string? false/c) = #f
Similar to send-url, but accepts a path to a file to be displayed by the browser. Use this function when you want to display a local file: it takes care of the peculiarities of constructing the correct file:// URL, and uses send-url to display the file. If you need to use an anchor fragment or a query string, use the corresponding keyword arguments.

(send-url/contents contents    
  [separate-window?    
  #:fragment fragment    
  #:query query    
  #:delete-at seconds])  void?
  contents : string?
  separate-window? : any/c = #t
  fragment : (or/c string? false/c) = #f
  query : (or/c string? false/c) = #f
  seconds : (or/c number? false/c) = #f
Similar to send-url/file, but it consumes the contents of a page to show, and displayes it from a temporary file.

If delete-at is a number, the temporary file is removed after this many seconds. The deletion happens in a thread, so if mzscheme exits before that it will not happen – when this function is called it scans old generated files (this happens randomly, not on every call) and removes them to avoid cluttering the temporary directory. If delete-at is #f, no delayed deletion happens, but old temporary files are still deleted as described above.

A parameter that, under Unix, determines the browser started send-url.

The parameter is initialized to the value of the 'external-browser preference.

The parameter value can be any of the symbols in unix-browser-list, #f to indicate that the preference is unset, or a pair of strings. If the preference is unset, send-url uses the first of the browsers from unix-browser-list for which the executable is found. If the parameter is a pair of strings, then a command line is constructed by concatenating in order the first string, the URL string, and the second string.

If the preferred or default browser can’t be launched, send-url fails. See get-preference and put-preferences for details on setting preferences.

(browser-preference? a)  boolean?
  a : any/c
Returns #t if v is a valid browser preference, #f otherwise. See external-browser for more information.

A list of symbols representing Unix executable names that may be tried in order by send-url. The send-url function internally includes information on how to launch each executable with a URL.