Lynx can be used to access information on the WWW, or to build information systems intended primarily for local access. For example, Lynx has been used to build several Campus Wide Information Systems (CWIS). In addition, Lynx can be used to build systems isolated within a single LAN.
In addition, a summary description of all the Lynx keystroke commands and their key bindings is available by pressing the 'K' key (or the 'k' key if vi-like key movement is not on). [ToC]
lynx filename
lynx /home/my-dir/filename
lynx ~/filename
When executed, Lynx will clear the screen and display as much of the specified file as will fit on the screen. Pressing a down-arrow will bring up the next screen, and pressing an up-arrow will bring up the previous screen. If no file is specified at startup, a default file will be displayed. (The default is configured by the system administrator when the command is installed.)
Lynx will display local files written in the HyperText Markup Language (HTML), if the file's name ends with the characters .html, .htm, .shtml, .htmlx, .html3, or .ht3. HTML is a file format that allows users to create a file that contains (among other things) hypertext links to other files. Several files linked together may be described as a hypertext document. If the filename does not have one of the suffixes mapped by Lynx to HTML, the -force_html command line option can be included to force treatment of the file as hypertext.
When Lynx displays an HTML file, it shows links as "bold face" text, except for one link, which is shown as "highlighted" text. Whether "boldface" or "highlighted" text shows up as reverse video, boldface type, or a color change, etc. depends on the display device being used (and the way in which that device has been configured). Lynx has no control over the exact presentation of links.
The one link displayed as "highlighted" text is the currently "selected" link. Lynx will display the file associated with the selected link when a right-arrow or a Return key is pressed. To select a particular link, press the up-arrow or down-arrow keys until the desired link becomes "highlighted," and then press the right-arrow or Return key to view the linked information. Information included in the HTML file tells Lynx where to find the linked file and what kind of server will provide it (i.e. HTTP, Gopher, etc.).
Lynx renders HTML files and saves the rendition, not the source, for initial display and should you select the link again. If you do select a link again and have reason to desire a new fetch and rendering of the file, use the NOCACHE command, normally mapped to 'x' and 'X', instead of the right-arrow or Return key when positioned on the link. You also can force a new fetch and rendering of the currently displayed document via the RELOAD command, normally mapped to Control-R.
When a binary file is encountered Lynx will ask the user if he/she wishes to download the file or cancel. If the user selects 'D' for download, Lynx will transfer the file into a temporary location and present the user with a list of options. The only default option is Save to disk, which is disabled if Lynx is running in anonymous mode. Any number of additional download methods may be defined in the lynx.cfg file by the system administrator. Programs like kermit, zmodem and FTP are some possible options. [ToC]
+-------+-------+-------+
| TOP | /|\ | Page |
arrow keys | of | | | UP |
| text 7| | 8| 9|
+---------+ +-------+-------+-------+
| SELECT | | | | |
| prev /|\| | <--- | | ---> |
| link | | | 4| 5| 6|
+---------+---------+---------+ +-------+-------+-------+
| BACK | SELECT | DISPLAY | | END | | | Page |
|<-- prev | next | | sel. -->| | of | | | DOWN |
| doc. | link \|/| link | | text 1| \|/ 2| 3|
+---------+---------+---------+ +-------+-------+-------+
There are also a few other keyboard commands to aid in navigation. The
Control and Function keys used for navigation within the current document
are described in Scrolling and Other useful commands. Some
additional commands depend on the fact that Lynx keeps a list of each
link you visited to reach the current document, called the History Page, and a
list of all links visited during the current Lynx session, called the Visited Links Page. The
HISTORY keystroke command, normally mapped to Backspace or
Delete, will show you the History Page of links leading to
your access of the current document. Any of the previous documents shown in
the list may be revisited by selecting them from the history screen. The
VLINKS keystroke command, normally mapped to uppercase 'V', will
show the Visited Links Page, and you similarly can select links in
that list. The MAIN_MENU keystroke command, normally mapped to 'm'
and 'M', will take you back to the starting document unless you
specified the -homepage=URL option at the command line. Also, the
LIST keystroke command, normally mapped to 'l' and L',
will create a compact list of all the links in the current document, and
they can be selected via that list.
The 'i' key presents an index of documents. The default index is usually a document pointing to servers around the world, but the index can be changed by the system administrator or on the command line using the -index=URL switch, and therefore depends on how the Lynx program you are using was configured.
If you choose a link to a server with active access authorization, Lynx will automatically prompt for a username and a password. If you give the correct information, you will then be served the requested information. Lynx will automatically send your username and password to the same server if it is needed again. [ToC]
Additional print options are available for users who are using Lynx from their own accounts (that is, so-called "non-anonymous users"). In particular, the Save to a local file option allows you to save the document into a file on your disk space. Any number of additional print options may also be available as configured by your system administrator.
Some options, such as Save to a local file, involve prompting for an output filename. All output filename entries are saved in a circular buffer, and any previous entries can be retrieved for re-use by pressing the up-arrow or down-arrow keys at the prompt.
Note that if you want exact copies of text files without any expansions of TAB characters to spaces you should use the Download options. [ToC]
Selecting the Print to a local file option from the Print Menu, makes it possible to save the source of the document to disk so that you may have a local copy of the document source, but it is better to Download the source.
NOTE: When saving an HTML document it is important to name the document with a .html extension, if you want to read it with Lynx again later.
Lynx can allow users to edit documents that reside on the local system. To enable editing, documents must be referenced using a "file:" URL or by specifying a plain filename on the command line as in the following two examples:
lynx file://localhost/FULL/PATH/FILENAME
lynx path/filename.html
Some options, such as Save to disk, involve prompting for an output filename. All output filename entries are saved in a circular buffer, and any previous entries can be retrieved for re-use by pressing the up-arrow or down-arrow keys at the prompt. [ToC]
The NOCACHE ('x' or 'X') command can be used in lieu of ACTIVATE (Return or right-arrow) to request an uncached copy and new rendition for the current link, or resubmission of a FORM, if a cache from a previous request or submission exits. The request or submission will include Pragma: no-cache and Cache-Control: no-cache in its headers. Note that FORMs with POST content will be resubmitted regardless of whether the NOCACHE or ACTIVATE command is used (see Lynx and HTML Forms). [ToC]
While viewing a normal document use the '/' command to find a word or phrase within the current document. The search type will depend on the search option setting in the Options Menu. The search options are case sensitive and case insensitive. These searches are entirely local to Lynx.
Some documents are designated index documents by virtue of an ISINDEX element in their HEAD section. These documents can be used to retrieve additional information based on searches using words or phrases submitted to an index server. The Lynx statusline will indicate that you are viewing such a document, and if so, the 's' key will invoke a statusline prompt to enter a query string. The prompt can be specified via a PROMPT attribute in the ISINDEX element. Otherwise, Lynx will use an internally configured prompt. The address for submitting the search can be specified via an HREF or ACTION attribute. Otherwise, Lynx will use the current document's URL and append your query string as a ?searchpart.
All search words or strings which you have entered during a Lynx session are saved in a circular buffer, and can be retrieved for re-use by pressing the up-arrow or down-arrow keys at the prompt for a search word or string. Also, you can use the 'n'ext command to repeat a search with the last-entered search word or phrase, starting from the current position in the document. The word or phrase matches will be highlighted throughout the document, but such highlighting will not persist for new documents, or if the current document is reloaded. The search cycles to the top of the document if the word or phrase is not located below your current position.
Although HTML Forms have largely replaced index
documents for searches via http servers, they are still useful for performing
searches directly via WAIS or Gopher servers in conjunction with the internal
gateways for such servers. For example, an HTML index document can act as a
cover page describing a WAIS database and how to formulate query
strings for searching it, and include an element such as: For fields where you must choose one of two choices, press any key
to toggle the choices and press the Return key to finish the
change.
For fields where you potentially have more than two choices, popup
windows may be evoked which function homologously to those for select
fields in HTML Forms. The popup windows will be invoked
only if you have popups for select fields set to ON (see below). Otherwise,
your cursor will be positioned at the current choice, and you can press any
key to cycle through the choices, then press the Return key to
finish the change.
When you are done changing options use the 'r' command to
return to Lynx or the '>' command to save the options to a
.lynxrc file and return to Lynx.
The following table describes the options available on the
Options Menu:
Once you have decided to send a comment or have selected a
mailto: link a new screen will appear showing you to whom you
are sending the message. Lynx will ask for your name, your e-mail
address, and the subject of the message. If you have filled in the
"personal mail address" field in the Options Menu, your e-mail
address will be filled in automatically. After entering the above
information, if you have an editor defined in the Options Menu
and you are not an anonymous user then your specified editor will be
spawned for you so that you can enter your message. If you do not have
an editor defined or you are an anonymous user, a simple line mode input
scheme will allow you to enter your message.
To finish sending the message, exit your spawned editor or, if you are
using the simple line mode input scheme, type a '.' (period) on
a line by itself. You will be asked a final time whether to send the
message. If you press 'y', you will be prompted whether to
append your signature file if one was defined in lynx.cfg and is accessible,
and then the message will be sent, whereas if you press 'n' the
message will be deleted. Entering Control-G in response to any prompts
also will cancel the mailing.[ToC]
To save a bookmark to the document you wish to place in the
bookmark file press the 'a' key and you will be asked:
A bookmark file will be created in conjunction with acting on the
'a'dd command if it does not already exist. Otherwise, the link
will be added to the bottom of the pre-existing bookmark file. You must
have created a bookmark file via the 'a'dd command before you
can view it.
Use the 'v' command to view the list of bookmarks you have
saved. While viewing the bookmark list you may select a bookmark as you
would any other link.
You can remove a link from the bookmark list by pressing the
'r' key when positioned on that link. You also can use a
standard text editor (e.g., via the 'e'dit command while viewing
a bookmark file, if an external editor has been defined via the Options
menu) to delete or re-order links in the bookmark file, or to modify
a link name by editing the content of the Anchor element for the
link, but you should not change the format within the line for the link,
consisting of an LI element followed by the Anchor
element, nor cause the line to become wrapped to a second line. You
similarly can change the link destination by editing the double-quoted
value for the HREF attribute in the Anchor start tag,
but you should not otherwise change the spacing within the start tag, nor
add other attributes. You can add a new link while editing by copying
an existing line for a link, to ensure the proper format, and then
modifying its HREF value and Anchor content, but you
should not add any other HTML markup to the bookmark file. If the format
and spacing (other than the Anchor content or HREF value)
within lines is changed or other HTML markup is added, the 'a'dd
and 'r'emove commands may not work properly.
When multi-bookmarks (see Options Menu) is OFF,
you will always view or add links to the default bookmark file. When
it is STANDARD, a menu of up to 26 bookmark files will be invoked,
and you select the bookmark file by entering its letter token. When
it is ADVANCED, you will be prompted for the letter token, but can
enter '=' to invoke the STANDARD selection menu, or
RETURN for the default bookmark file.
[ToC]
All jump shortcut entries are saved in a circular buffer, and any
previous entries can be retrieved for re-use by pressing the
up-arrow or down-arrow keys at the prompt.
Note to System Administrators: Read the lynx.cfg file on how
to set up the jump command for your system and how to define shortcut names.
[ToC]
An HTML Form provides for the use of buttons to perform an action
(such as submit), checkboxes, radio buttons or popups to select
options from a list, and fields for entering text.
NOTE: If you have a text input field selected you will not
have access to most of the Lynx keystroke commands, because they are
interpreted by the Line Editor as either text entries or editing commands. Select a
button or box when you want to use Lynx keystrokes.
To submit the form press
right-arrow or Return when positioned on the form's
submit button. If you've submitted the form previously during the Lynx
session, have not changed any of the form content, and the METHOD was
GET, Lynx will retrieve from its cache what was returned from the
previous submission. If you wish to resubmit that form to the server with
the same content as previously, use the RESUBMIT command ('x') when
positioned on the submit button. The right-arrow and Return
keys also will invoke a no-cache resubmission if the reply from a form
submission included a META element with a no-cache Pragma or Cache-Control
directive: You also can use the DOWNLOAD ('d') keystroke command when
positioned on a form submit button if you wish to download the server's
reply to the submission instead of having Lynx render and display it.
Forms which have POST as the METHOD, or a
mailto: URL as the ACTION, are always
resubmitted, even if the content has not changed, when you activate the
submit button. Lynx normally will not resubmit a form which has
POST as the METHOD if the document returned by the form has links
which you activated, and then you go back via the PREV_DOC
(left-arrow) command or via the History Page. Lynx can be
compiled so that it resubmits the form in those cases as well, and the default
can be changed via lynx.cfg, and toggled via the
-resubmit_posts command line switch.
If the form has one text entry field and no other fields except,
possibly, hidden INPUT fields not included in the display, then that field
also serves as a submit button, and pressing right-arrow
or Return on that field will invoke submission of the form. Be
sure to use up-arrow, down-arrow or TAB to move
off the text entry field, in such cases, if it is not your intention to
submit the form (or to retrieve what was returned from an earlier submission
if the content was not changed and the METHOD was GET).
Forms can have multiple submit buttons, if they have been
assigned NAMEs in the markup. In such cases, information about which
one of the buttons was used to submit the form is included in the form
content.
Inlined images can be used as submit buttons in forms. If such
buttons are assigned NAMEs in the markup, for graphic clients they can
also serve as image maps, and the x,y coordinates of
the graphic client's cursor position in the image when it was
clicked are included in the form content. Since Lynx cannot
inline the image, and the user could not have moved a cursor from the
origin for the image, if no alternatives are made available in the
markup Lynx sends a 0,0 coordinate pair in the form content. Document
authors who use images as submit buttons, but have at least some concern
for text clients and sight-challenged Webizens, should include VALUEs for
the buttons in such markup. Lynx will then display the string assigned
to the VALUE, as it would for a normal submit button. Some document
authors incorrectly use an ALT instead of VALUE attribute for this purpose.
Lynx "cooperates" by treating ALT as a synonym for VALUE when present in
an INPUT tag with TYPE="image". If neither a VALUE nor an ALT attribute
is present, Lynx displays "[IMAGE]-Submit" as the string for such buttons.
If clickable images is set, the "[IMAGE]" portion of the string is a link
for the image, and the "Submit" portion is the button for submitting the
form. Otherwise, the entire string is treated as a submit button. If
a VALUE or ALT attribute is present and clickable images is set, Lynx
prepends "[IMAGE]" as a link for the image, followed by '-' and then
the attribute's value as the displayed string for the submit button.
Note that earlier versions of Lynx would send a name=value pair instead of
a 0,0 coordinate pair if a TYPE="image" submit button was NAME-ed, had a
VALUE attribute in the INPUT tag, and was used to submit the form. The
script which analyzes the form content thus could be made aware whether
the submission was by a user with a graphic client and had image loading
turned on, or by a user who did not see the image nor make a conscious
choice within it. However, requests that this be included in HTML
specifications consistently have fallen on deaf ears, and thus Lynx now
"fakes" a 0,0 coordinate pair whether or not a VALUE or ALT attribute is
present in the INPUT tag. Ideally, the script which analyzes the submitted
content will treat the 0,0 coordinate pair as an indicator that the user
did not see the image and make a conscious choice within it.
Forms can have hidden INPUT fields, which are not displayed,
but have NAMEs and VALUEs included in the content. These often are used
to keep track of information across a series of related form submissions,
but have the potential for including information about the user that might
be considered to represent an invasion of privacy. NOTE, in this regard,
that Lynx has implemented the HTML 3.0
DISABLED attribute for all of its form fields. These
can be used to keep track of information across submissions, and to cast
it unmodifiable in the current form, but keep the user aware that it will
be included in the submission.
Forms most commonly are submitted to http servers with the content encoded
as ENCTYPE="application/x-www-form-urlencoded" for analysis by a
script, and Lynx treats that as the default if no ENCTYPE is specified in the
FORM start tag. However, you can specify a mailto URL as the form's ACTION to
have the form content sent, instead, to an email address. In such cases, you
may wish to specify ENCTYPE="text/plain" in the form markup, so that
the content will not be encoded, but remain readable as plain text.
Lynx also supports ENCTYPE="application/sgml-form-urlencoded"
for which all reserved characters in the content will be hex escaped, as
with application/x-www-form-urlencoded, but semicolons
(';') instead of ampersands ('&') will be used as
the separator for name=value pairs in the form content. The use of
semicolons is preferred for forms with the GET METHOD, because
the GET METHOD causes the encoded form content to be appended
as a ?searchpart for the form's ACTION, and if such URLs are used
in text/html documents or bookmark files without conversion
of the ampersands to SGML character references (& or
&), their being followed by form field NAMEs which might
correspond to SGML entities could lead to corruption of the intended URL.
NOTE, in this regard, that Lynx converts ampersands to &
when creating bookmarks, and thus the bookmark links will not be vulnerable
to such corruptions. Also NOTE that Lynx allows you to save links in your
bookmark file for documents returned by forms with the GET METHOD,
and which thus have the content appended as a ?searchpart, but not
if the METHOD was POST, because the content would be lost and the
link thus would be invalid.
Lynx supports ENCTYPE="multipart/form-data" for sending form
content with name=value pairs encoded as multipart sections with individual
MIME headers and boundaries. However, Lynx does not yet support INPUTs
with TYPE="file" or TYPE="range" and
will set the DISABLED attribute for all of the form's fields if
any INPUTs with either of those two TYPEs are present, so that the form
can't be submitted. Otherwise, Lynx will submit the form with the multipart
ENCTYPE.
A Content-Disposition: file; filename=name.suffix
header can be used by CGI scripts to set the suggested filename offered
by Lynx for 'd'ownload and 'p'rint menu options to save
or mail the body returned by the script following submission of a FORM.
Otherwise, Lynx uses the last symbolic element in the path for the FORM's
ACTION, which is normally the script, itself, or a PATH_INFO field, and
thus might be misleading. This also can be done via a META element in
any document:
Lynx recognizes the TABLE element and all of its associated elements
as described in ftp://ds.internic.net/rfc/rfc1942.txt
and will process any ID attributes in the start tags for handling as NAME-ed
anchors, but does not create actual tables. Instead, it treats
the TR start tag as a collapsible BR (line break), and inserts a collapsible
space before the content of each TH and TD start tag. This generally makes
all of the content of the table readable, preserves most of the
intra-cell organization, and makes all of the links in the table
accessible, but any information critically dependent on the column and row
alignments intended for the table will be missed.
If inherently tabular data must be presented with Lynx, one can use PRE
formatted content, or, if the table includes markup not allowed
for PRE content, construct the table using HTML Tabs. An example table using TAB
elements is included in the test subdirectory of the Lynx distribution.
[ToC]
Note that this Users Guide includes TAB markup in
a manner which degrades gracefully for WWW browsers which do not
support it. Toggle to display of source and search for <tab to examine the use of TAB markup
in these documents. [ToC]
Lynx recognizes the Netscape and MicroSoft Explorer FRAME, FRAMESET,
and NOFRAMES elements, but is not capable of windowing to create the
intended positioning of frames. Instead, Lynx creates labeled
links to the frame sources, typically positioned in the upper
left corner of the display, and renders the NOFRAMES section. If the
document provider has disregard for text clients and sight-challenged
Webizens, and thus does not include substantive content in the NOFRAMES
section or a link in it to a document suitable for text clients, you
can usually guess from the labeling of the frame links which
one has the substantive material (if there is any), or you can try each
of those links to see if anything worthwhile is returned.
[ToC]
Lynx recognizes and processes all of the HTML 3.0
REL attribute tokens in LINK elements for creating a banner, and
a number of others which have subsequently been proposed. These
banner tokens are Home, ToC, Contents,
Index, Glossary, Copyright, Up,
Next, Previous, Prev, Help,
Search, Top, Origin, Navigator,
Child, Disclaimer, Sibling, Parent,
Author, Editor, Publisher, Trademark,
Meta, URC, Hotlist, Begin,
First, End, Last, Pointer,
Translation, Definition, Chapter,
Documentation, Biblioentry, Bibliography,
Bookmark and Banner. Any LINK elements with those
tokens as the REL attribute value, and an HREF attribute value in the LINK,
will invoke creation of a banner at the top of the first page,
with the element's HREF as the link, and the token as the default link
name. If a TITLE attribute is included in the LINK, it's value will be
used as the link name instead of the default. Bookmark and
Banner are intended to be accompanied by a TITLE attribute,
which in effect makes the namespace for REL banner tokens
infinite.
If the special token Help is used as the REL value and no HREF
is included in the LINK, Lynx will use it own HELPFILE URL for that
link. For the special token Home without an HREF, Lynx will use
the default STARTFILE (i.e., derived from the configuration files
or the WWW_HOME environment variable, not the command line
startfile if one was used). However, if a -homepage=URL
was specified on the command line, it's URL will be used as the HREF.
For the special token Index without an HREF, Lynx will use the
DEFAULT_INDEX_FILE derived from the configuration files, or if an
-index=URL was specified on the command line, it's URL will be used
as the HREF.
Lynx does not waste screen real estate maintaining the banner at
the top of every page, but the Lynx TOOLBAR keystroke command ('#')
will, any time it is pressed, position you on the banner so that
any of its links can be activated, and pressing the left-arrow when
in the banner will return you to where you were in the current
document. The toolbar is indicated by a '#" preceding its first
link when present on the screen, that is, when the first page of the
document is being displayed. The availability of a toolbar is indicated by
a '#' at the top, left-hand corner of the screen when the second
or subsequent pages of the document are being displayed.
Lynx also recognizes the HTML 3.0
BANNER container element, and will create a banner based on its
content if one has not already been created based on LINK elements. Lynx
treats the MicroSoft MARQUEE element as a synonym for BANNER (i.e.,
presenting it's markup as a static banner, without any horizontal
scrolling of its content). Lynx does not prefix the BANNER or MARQUEE
content with a '#' because the content need not be only a series
of links with brief, descriptive links names, but does add a '#'
at the top, left-hand corner of the screen when the content is not being
displayed, to indicate it's accessibility via the TOOLBAR keystroke command.
[ToC]
i.e., position it at the top of the page. Then, upon reading the footnote,
you can return to your previous position in the document by pressing the
left-arrow key. The content of an FN element can be any HTML
markup that is valid in the BODY of the document.
[ToC]
Lynx also supports the TYPE attribute for OL elements, which can have
values of 1 for Arabic numbers, I or i for
uppercase or lowercase Roman numerals, or A or a for
uppercase or lowercase letters, that increment for successive LI elements
in the list block. The CONTINUE attribute can be used to continue the
ordering from the preceding list block when the nesting depth is changed.
Lynx treats the OL attributes START and SEQNUM as synonyms for specifying
the ordering value for the first LI element in the block. The values should
be specified as Arabic numbers, but will be displayed as Arabic, Roman, or
alphabetical depending on the TYPE for the block. The values can range from
-29997 to the system's maximum positive integer for Arabic numbers.
For Roman numerals, they can range from 1 (I or i)
to 3000 (MMM or mmm.). For alphabetical orders,
the values can range from 1 (A or a) to
18278 (ZZZ or zzz). If the CONTINUE attribute is
used, you do not need to specify a START or SEQNUM attribute to extend the
ordering from a previous block, and you can include a TYPE attribute to
change among Arabic, Roman, or alphabetical ordering styles, or their casing,
without disrupting the sequence. If you do not include a START, SEQNUM or
CONTINUE attribute, the first LI element of each OL block will default to
1, and if you do not include a TYPE attribute, Lynx defaults to
Arabic numbers.
For UL blocks without the PLAIN attribute, Lynx uses *,
+, o, #, @ and - as
bullets to indicate, progressively, the depth within the six
nesting levels.
Lynx treats UL, OL, DIR, and MENU blocks as having the COMPACT attribute
by default, i.e., single spaces between LH and LI elements within those
blocks. For DL blocks, double spacing will be used to separate the DT and
DD elements unless the COMPACT attribute has been specified.
[ToC]
Lynx renders block quotes with a greater than normal left and right
indentation. Lynx does not support italics, and normally substitutes
underlining, but does not underline block quotes so as not to obscure any
explicit emphasis elements within the quotation. The BLOCKQUOTE or BQ
block can include a CREDIT container element, whose content will be rendered
as an implied new paragraph with a CREDIT: label at the beginning of
its first line.
Lynx respects nested Q start and end tags, and will use ASCII double-quotes
(") versus grave accent (`) and apostrophe
('), respectively, for even versus odd depths in the nest.
Any ID attributes in BLOCKQUOTE, BQ or Q elements will be treated as
named Anchors. [ToC]
Newer HTML markup provides bases for the client to determine the
URLs associated with areas in the image map, and/or for a text client
to process alternative markup and allow the user to make choices based
on textual information. These have been termed
client-side-image-maps.
Lynx recognizes and processes the MAP container element and its AREA
elements, and will create a menu of links for the HREF of each AREA when
the link created for the IMG element with a USEMAP attribute is activated.
The menu uses the ALT attributes of the AREA elements as the link names,
or, if the document's author has disregard for text clients and
sight-challenged Webizens, and thus did not include ALT attributes, Lynx
uses the resolved URLs pointed to by the HREF attributes as the link names.
Lynx uses the TITLE attribute of the IMG element, or the TITLE attribute of
the MAP, if either was present in the markup, as the title and main header
of the menu. Otherwise, it uses the ALT attribute of the IMG element. If
neither TITLE nor ALT attributes were present in the markup, Lynx creates
and uses a [USEMAP] pseudo-ALT. The MAPs need not be in the same
document as the IMG elements. If not in the same document, Lynx will fetch
the document which contains the referenced MAP, and locate it based on
its NAME or ID attribute. All MAPs encountered in documents during a
Lynx session are cached, so that they need not be retrieved repeatedly
when referenced in different documents.
If the IMG element also indicates a server-side-image-map
via an ISMAP attribute, Lynx normally will create a link for that as well,
using an [ISMAP] pseudo-ALT (followed by a hyphen to indicate its
association with the client-side-image-map) rather than ignoring
it, and will submit a 0,0 coordinate pair if that link is activated.
Although, the client-side-image-map may be more useful for a
client such as Lynx, because all of the URLs associated with the image
map can be accessed, and their nature indicated via ALT attributes,
Lynx-friendly sites can map 0,0 such that the server returns a
for-text-client document homologous to the content of FIG elements (see
below). Inclusion of such a link for submissions to the server can be
disabled by default via the configuration file (lynx.cfg), and the
default can be toggled via the -ismap command line switch.
Lynx also recognizes the HTML 3.0
FIG and OVERLAY elements, and will handle them as intended for text clients.
These are the ideal way to handle client-side-image-maps, because
the FIG content provides complete alternative markup, rather than relying
on the client to construct a relatively meager list of links with link
names based on ALT strings.
The presently experimental OBJECT element encompasses much of the
functionality of the FIG element for client-side-image-maps.
Lynx will render and display the content of OBJECT elements which have
the SHAPES attribute equivalently to its handling of FIG. Lynx also
handles OBJECT elements with the USEMAP and/or ISMAP attributes
equivalently to its handling of IMG elements with
client-side-image-maps and/or server-side-image-maps.
[ToC]
Lynx recognizes and processes Refresh directives in META
elements, but puts up a labeled link, typically in the upper left corner
of the display, indicating the number of seconds intended before a
refresh, and the URL for the refresh, instead of making the request
automatically after the indicated number of seconds. This allows
people using a braille interface any amount of time to examine the
current document before activating the link for the next URL. In
general, if the number of seconds indicated is short, the timing
is not critical and you can activate the link whenever you like.
If it is long (e.g., 60 seconds), a server process may be generating
new documents or images at that interval, and you would be wasting
bandwidth by activating the link at a shorter interval.
[ToC]
State Management via cookie exchanges originally was implemented by
Netscape, and such cookies are now designated as Version 0. A
more elaborate format for cookies, designated as Version 1, is
being standardized by the IETF (Internet Engineering Task Force). Lynx
supports both Version 0 and Version 1 cookie exchanges.
This support can be disabled by default via the SET_COOKIES symbol in the
compilation (userdefs.h) and/or run time (lynx.cfg)
configuration files, and that default setting can be toggled via the
-cookies command line switch.
When cookie support is enabled, Set-Cookie MIME headers
received from an http server invoke confirmation prompts with possible
replies of 'Y'es or 'N'o for acceptance of the cookie,
'A'lways to accept the cookie and to allow all subsequent
cookies from that domain (server's Fully Qualified Domain Name,
or site-identifying portion of the FQDN) without further confirmation
prompts, or ne'V'er to never allow cookies from that
domain to be accepted (silently ignore its Set-Cookie
MIME headers). All unexpired cookies are held in a hypothetical
Cookie Jar which can be examined via the COOKIE_JAR keystroke
command, normally mapped to Ctrl-K, for invoking the Cookie Jar Page. The
Cookie Jar, and any 'A'lways or ne'V'er
'allow' settings, do not presently outlast the Lynx session.
A common use of cookies by http servers is simply to track the
documents visited by individual users. Though this can be useful to the
site's WebMaster for evaluating and improving the organization of links
in the various documents of the site, if the user has configured Lynx
to include a From MIME header with the user's email address in
http requests, or has passed personal information to the server via a
form submission, the tracking might be used to draw inferences, possibly
incorrect, about that user, and may be considered by some as an invasion
of privacy.
An example of worthwhile State Management via cookies is the setting
of personal preferences, typically via a form submission to the site,
which will then apply to all documents visited at that site.
If you accept cookies when accessing a site, but are given no indication
about how they will be used in subsequent requests to that site, nor can
infer how they will be used, you can Gobble (delete) the cookies
and/or change the 'allow' setting for its domain via the Cookie Jar Page.
[ToC]
This distributed approach let providers retain complete control
over their information, but it made communication between users
and providers somewhat more difficult. Following the lead of Neal
Erdwien, of Kansas State University, the Lynx hypertext format was
extended to include links for including ownership information with
each file. This information made it possible for users running
Lynx clients to send comments and suggestions via e-mail to the
providers.
This early version of Lynx was also augmented to support hypertext
links to programs running on remote systems. It included the ability
to open a Telnet connection, as well as the ability to start programs
via rexec, inetd, or by direct socket connects. These capabilities were
included to allow users to access databases or custom program interfaces.
A subsequent version of Lynx incorporated the World Wide Web libraries
to allow access to the full list of WWW servers, along with the option to
build hypertext documents in HTML, rather than the native Lynx format.
HTML has become far more widely used, and the native format has been phased
out. With the addition of the WWW libraries, Lynx became a fully-featured
WWW client, limited only by the display capabilities offered in the curses
environment.
Lynx was designed by Lou Montulli, Charles Rezac and Michael Grobe
of Academic Computing Services at The University of Kansas. Lynx was
implemented by Lou Montulli and maintained by Garrett Arch Blythe and
Craig Lavender.
Foteos Macrides and members of the lynx-dev list have
developed and supported Lynx since release of v2.3
in May 1994. The Lynx2-3FM code set was released as v2.4 in June 1995.
The Lynx2-4FM code set was released as v2.5 in May 1996. The Lynx2-5FM
code set was released as v2.6 in September 1996. The Lynx2-6FM code set
was released as v2.7 in February 1997, and v2.7.1 with bug fixes for v2.7
was released in April 1997.
Lynx has incorporated code from a variety of sources along the
way. The earliest versions of Lynx included code from Earl Fogel
of Computing Services at the University of Saskatchewan, who
implemented HYPERREZ in the Unix environment. Those versions also
incorporated libraries from the Unix Gopher clients developed at
the University of Minnesota, and the later versions of Lynx rely
on the WWW client library code developed by Tim Berners-Lee (and
others) and the WWW community.
Information on obtaining the most current version of Lynx is available
via Lynx links.
[ToC]
for submitting a search of the Biologist's Addresses database directly
to the net.bio.net WAIS server. [ToC]
Lynx Options Menu
The Lynx Options Menu may be accessed by pressing the 'o'
key. The current Options Menu contains the following configurable
options.
Options Menu
E)ditor : emacs
D)ISPLAY variable : aixtest.cc.ukans.edu:0.0
mu(L)ti-bookmarks: OFF B)ookmark file: lynx_bookmarks.html
F)TP sort criteria : By Filename
P)ersonal mail address : montulli@netscape.com
S)earching type : CASE INSENSITIVE
preferred document lan(G)uage: en
preferred document c(H)arset : NONE
display (C)haracter set : ISO Latin 1
raw 8-bit or CJK m(O)de : ON show color (&) : OFF
V)I keys: OFF e(M)acs keys: OFF sho(W) dot files: OFF
popups for selec(T) fields : ON show cursor (@) : OFF
K)eypad mode : Numbers act as arrows
li(N)e edit style : Default Binding
l(I)st directory style : Mixed style
U)ser mode : Advanced
user (A)gent : [User-Agent header]
local e(X)ecution links : FOR LOCAL FILES ONLY
An option can be changed by entering the capital letter or character in
parentheses for the option you wish to change (e.g. 'E' for Editor
or '@' for show cursor). For fields where text must be entered,
simply enter the text by typing on the keyboard. The Line Editor can be used to
correct mistakes, and Control-U can be used to erase the whole
line. When you are done entering a change press the Return key
to get back to the Command? prompt.
By Filename", "By Size",
"By Type", and "By Date".
ALWAYS and
NEVER are not offered in anonymous accounts. If saved to a
.lynxrc file in non-anonymous accounts, ALWAYS will
cause Lynx to set color mode on at startup if supported.
If Lynx is built with the slang library, this is equivalent to
having included the -color command line switch or having the
COLORTERM environment variable set. If color support is
provided by curses or ncurses, this is equivalent to the default
behavior of using color when the terminal type supports it.
If (n)curses color support is available but cannot be used for
the current terminal type, the preference can still be saved
but will have no effect.
A saved value of NEVER will
cause Lynx to assume a monochrome terminal at startup.
It is similar to the -nocolor switch, but (when the
slang library is used) can be overridden with the -color
switch.
If the setting is OFF or ON
when the current options are saved to a .lynxrc file,
the default startup behavior is retained, such that color mode
will be turned on at startup only if the terminal info indicates
that you have a color-capable terminal, or (when the
slang library is used) if forced on via the
-color switch or COLORTERM variable. This
default behavior always is used in anonymous accounts, or if
the option_save restriction is set explicitly. If
for any reason the startup color mode is incorrect for your
terminal, set it appropriately on or off via this option.
Follow link (or page) number: and
Select option (or page) number:
help for more information.
Comments and mailto: links
At any time while viewing documents within Lynx, you may use the
'c' command to send a mail message to the owner of the current
document if the author of the document has specified ownership. If no
ownership is specified then comments are disabled. Certain links called
mailto: links will also allow
you to send mail to other people. Using the mail features within Lynx is
straightforward.
Lynx bookmarks
It is often useful to place a bookmark to aid in returning quickly to
a document. To use the bookmark feature you must first use the
Options Menu to specify a bookmark filename.
Save D)ocument or L)ink to bookmark file or C)ancel? (d,l,c):
Answer 'd' to save a link to the document you are currently
viewing or 'l' to save the link that is currently selected on
the page. Selecting 'c' will cancel without saving anything to
your bookmark file.
Jump Command
A feature similar to the Lynx bookmarks is the jump command. The jump
command allows you to enter a shortcut name to access a URL. If the jump
feature is active, typing 'j' will produce a prompt where you may
enter the shortcut name. Type '?' at the jump prompt for a list
of shortcut names available.
Directory Editing
Lynx offers extended DIRED support on Unix (on VMS the more powerful
CSwing program is recommended for character cell terminals, and can be
offered via Lynx as a jump shortcut or execution link). When a local
directory is accessed using a URL of the form
file://localhost/path/, a new set of commands is available.
With DIRED support you can create, edit, delete, copy, and move files
on your local system. The commands available in DIRED mode are
[ToC]
C)reate
D)ownload
E)dit
F)ull Menu
M)odify
R)emove
T)ag
U)pload
Scrolling and Other useful commands
A summary of all the keystroke commands and their key bindings can
be invoked via the KEYMAP command, normally mapped to 'k' and
'K'. The following describes some of the most commonly used
commands.
Select option (or page) number:
prompts.
[ToC]
Lynx and HTML Forms
This section describes the Lynx Forms Interface. HTML gives document
providers the ability to create on-line forms which may be filled out
when the document is viewed. When a form is submitted the information
on the form can be used to search a database or complete a survey.
In general, you can move around the form using the standard Lynx navigation
keys. The up-arrow and down-arrow keys, respectively,
select the previous or next field, box, or button. The TAB key
selects the next field (or next page of a TEXTAREA if it extends onto the
next page), box, or button.
or the server sent a "Pragma" or "Cache-Control" MIME header with a
no-cache directive.
[ToC]
Lynx and HTML Tables
HTML includes markup for creating tables structured as arrays of
cells aligned by columns and rows on the displayed page.
Lynx and HTML Tabs
Lynx implements the HTML 3.0
TAB element only when LEFT alignment is in effect. If the alignment is
CENTER or RIGHT (JUSTIFY is not yet implemented in Lynx, and is treated
as a synonym for LEFT), or if the TAB element indicates a position to the
left of the current position on the screen, it is treated as a collapsible
space. For purposes of implementing TAB, Lynx treats en units as
half a character cell width when specified by the INDENT attribute, and
rounds up for odd values (e.g., a value of either 5 or 6 will be treated
as three spaces, each the width of a character cell). See the example
table using TAB elements in the test subdirectory of the Lynx
distribution as a model for using this functionality.
Lynx and HTML Frames
Some implementations of HTML include markup, primarily designed for graphic
clients, that is intended to create an array of simultaneously displayed,
independently scrolling windows. Such windows have been termed
frames.
Lynx and HTML Banners
Some implementations of HTML markup include provisions for creating a
non-scrolling window to be positioned at the top of each page, containing
links with brief, descriptive link names, analogous to a Windows toolbar.
Such windows have been termed banners.
Lynx and HTML Footnotes
Lynx implements the HTML 3.0
FN element similarly to a named Anchor within the current document,
and assumes that the footnotes will be positioned at the bottom of the
document. However, in contrast to named Anchors, the FN container
element is treated as a block (i.e., as if a new paragraph were indicated
whether or not that is indicated in its content) with greater than normal
left and right margins, and the block will begin with a FOOTNOTE:
label. For example, if the document contains:
activating that link will take you to the labeled rendering of:
Lynx and HTML Notes
Lynx implements the HTML 3.0
NOTE element (Admonishment) as a labeled block, i.e., as if a new
paragraph were indicated whether or not paragraphing markup is included
in its content, with greater than normal left and right margins, and with
the type of note indicated by an emphasized label based on the value of its
CLASS or ROLE attribute. If no CLASS or ROLE attribute is included, the
default label NOTE: will be used. Lynx recognizes the values
caution and warning, for which, respectively, the labels
CAUTION: or WARNING: will be used. The NOTE element can
have an ID attribute, which will be treated as a named Anchor, as
for HTML Footnotes, but the NOTE block need not be placed
at the bottom of the document. The content of a NOTE block can be any HTML
markup that is valid in the BODY of the document. This is an example:
It will degrade gracefully for WWW browsers which do not support
NOTE, except for recognition of the ID attribute as a named Anchor.
[ToC]
Lynx and HTML Lists
Lynx implements the HTML 3.0
list elements UL (Unordered List), OL (Ordered List),
and DL (Definition List), and their associated attributes, and
elements (LH, LI, DT, and DD) for the most part as described in that
specification. The lists can be nested, yielding progressively greater
indentation, up to six levels. The HTML 2.0 MENU and DIR elements both are treated as synonyms
for UL with the PLAIN attribute (no bullets, see below). Note,
thus, that neither DIR nor MENU yields a series of columns with 24-character
spacing. A single nesting index is maintained, so that different types of
List elements can be used for different levels within the nest. Also, the
HTML 3.0
FIG, CAPTION and CREDIT elements are treated as valid within list blocks.
They will be rendered with indentation appropriate for the current nesting
depth, and the CAPTION or CREDIT elements will have a CAPTION: or
CREDIT: label beginning the first line of their content. The
content of any APPLET or OBJECT elements in the lists also will be indented
appropriately for the current nesting depth, but those will not invoke line
breaks unless indicated by their content, and it should not include markup
which is inappropriate within the list.
Lynx and HTML Quotes
The HTML 3.0 and
later specifications provide for two classes of quotation in HTML documents.
Block quotes, designated by the BLOCKQUOTE element (or it's abbreviated
synonym BQ in HTML 3.0), have implied paragraph breaks preceding and following
the start and end tags for the block. Character level quotes, designated by
the Q element, in contrast are simply directives in the markup to insert an
appropriate quotation mark.
Lynx and Client-Side-Image-Maps
HTML includes markup, designed primarily for graphic clients, that treats
inlined images as maps, such that areas of the image within which a mouse
cursor was positioned when the mouse was clicked can correspond
to URLs which should be retrieved. The original implementations
were based on the client sending an http server the x,y coordinates
associated with the click, for handling by a script invoked by
the server, and have been termed server-side-image-maps. Lynx
has no rational way of coping with such a procedure, and thus simply
sends a 0,0 coordinate pair, which some server scripts treat as an
instruction to return a document suitable for a text client.
Lynx and Client-Side-Pull
HTML includes provision for passing instructions to clients via directives
in META elements, and one such instruction, via the token Refresh,
should invoke reloading of the document, fetched from a server with the
same URL or a new URL, at a specified number of seconds following receipt
of the current document. This procedure has been termed
client-side-pull. An example of such an element is:
which instructs a client to fetch the indicated URL in 3 seconds after
receiving the current document. If the URL= field is omitted,
the URL defaults to that of the current document. A no-cache
directive is implied when the Refresh if for the same URL.
Lynx State Management
(Me want cookie!)
HTTP provides a means to carry state information across successive
connections between a browser and an http server. Normally, http servers
respond to each browser request without relating that request to previous
or subsequent requests. Though the inclusion of INPUT fields with
TYPE="hidden" can be used as a sort of state management by HTML Forms, a more general approach involves exchanges of MIME
headers between the server and browser. When replying to a request,
the server can send a Set-Cookie MIME header which contains
information (cookies) relevant to the browser's request, and in
subsequent requests the browser can send a Cookie MIME header
with information derived from previously received cookies.
Lynx development history
Lynx grew out of efforts to build a campus-wide information system
at The University of Kansas. The earliest versions of Lynx provided a
user-friendly, distributed hypertext interface for users connected to
multiuser (Unix and VMS) systems via curses-oriented display devices.
A custom hypertext format was developed to support hypertext links to
local files and files on remote Gopher servers. Using Gopher servers
for distributed file service allowed information providers to publish
information from a wide variety of platforms (including Unix, VMS,
VM/CMS and Macintosh). In addition, Lynx became the most user-friendly
Gopher client, although that was only an ancillary capability.