5 Send URL: Opening a Web Browser

▼ |  | Net: Networking Libraries

1 | HTTP Client
2 | URLs and HTTP
3 | URI Codec: Encoding and Decoding URIs
4 | FTP: Client
5 | Send URL: Opening a Web Browser
6 | SMTP: Sending E-Mail
7 | sendmail: Sending E-Mail
8 | Headers: Parsing and Constructing
9 | Header Field Encoding
10 | IMAP: Reading Mail
11 | POP3: Reading Mail
12 | MIME: Decoding Internet Data
13 | Base 64: Encoding and Decoding
14 | Quoted-Printable: Encoding and Decoding
15 | DNS: Domain Name Service Queries
16 | NNTP: Newsgroup Protocol
17 | TCP: Unit and Signature
18 | TCP Redirect: tcp^ via Channels
19 | SSL Unit: tcp^ via SSL
20 | CGI Scripts
21 | Cookie: Legacy HTTP Client Storage
22 | Git Repository Checkout
| Bibliography
| Index

On this page:

send-url
send-url/ file
send-url/ contents
send-url/ mac
external-browser
browser-preference?
unix-browser-list

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### 5`` Send URL: Opening a Web Browser

(require net/sendurl) | package: net-lib

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

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

> > procedure
> > (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.

On 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.)

On Mac OS, send-url calls send-url/mac.

On Unix, send-url uses a user-preference, or when none is set, it will look for a known browser. See the description of external-browser for details.

If escape? is true, then str is escaped (by UTF-8 encoding followed by “%” encoding) to avoid dangerous shell characters: single quotes, double quotes, backquotes, dollar signs, backslashes, non-ASCII characters, and non-graphic characters. Note that escaping does not affect already-encoded characters in str.

On all platforms, external-browser parameter can be set to a procedure to override the above behavior — the procedure will be called with the url string.

> > procedure
> > (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 (with #:escape? #t), but accepts a path to a file to be displayed by the browser, along with optional fragment (with no leading #) and query (with no leading ?) strings. Use send-url/file to display a local file, since it takes care of the peculiarities of constructing the correct file:// URL.

The path, fragment, and query arguments are all encoded in the same way as a path provided to send-url, which means that already-encoded characters are used as-is.

> > procedure
> > (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 displays it from a temporary file.

When send-url/content is called, it scans old generated files (this happens randomly, not on every call) and removes them to avoid cluttering the temporary directory. If the #:delete-at argument is a number, then the temporary file is more eagerly removed after the specified number of seconds; the deletion happens in a thread, so if Racket exits earlier, the deletion will not happen. If the #:delete-at argument is #f, no eager deletion happens, but old temporary files are still deleted as described above.

> procedure (send-url/mac url [#:browser browser]) → void?
> url : string?
> browser : (or/c string? #f) = #f

Like send-url, but only for use on a Mac OS machine.

The optional browser argument, if present, should be the name of a browser installed on the system. For example,

> (send-url/mac "http://www.google.com/" #:browser "Firefox")

would open the url in Firefox, even if that’s not the default browser. Passing #f means to use the default browser.

This function looks in "com.apple.launchservices.secure.plist" in the user’s home directory for a LSHandlerURLScheme key for either http or https and then, looks for a LSHandlerRoleAll key that is one of a list of known browsers. If it finds such a browser, it uses the AppleScript command tell application ... to open location to send the url to the browser. Otherwise, it uses just open location to send the url to the browser.

> parameter (external-browser) → browser-preference?
> (external-browser cmd) → void?
> cmd : browser-preference?

A parameter that can hold a procedure to override how a browser is started, or #f to use the default platform-dependent command.

On Unix, the command that is used depends on the 'external-browser preference. If the preference is unset, send-url uses the first of the browsers from unix-browser-list for which the executable is found. Otherwise, the preference should hold a symbol indicating a known browser (from the unix-browser-list), or it a pair of a prefix and a suffix string that are concatenated around the url string to make up a shell command to run. In addition, the external-browser paremeter can be set to one of these values, and send-url will use it instead of the preference value.

Note that the URL is encoded to make it work inside shell double-quotes: URLs can still hold characters like #, ?, and &, so if the external-browser is set to a pair of prefix/suffix strings, they should use double quotes around the url.

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

> procedure (browser-preference? a) → boolean?
> a : any/c

Returns #t if v is a valid browser preference, #f otherwise. See external-browser for more information.

> value unix-browser-list : (listof symbol?)

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.
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