charon man page on Inferno

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CHARON(1)							     CHARON(1)

NAME
       charon - web browser

SYNOPSIS
       charon [ -option [value] ] [url]

DESCRIPTION
       Charon  is  the	Inferno graphical web browser, supporting a variety of
       web standards for the download, viewing, automation and	navigation  of
       web based information and images.

       The  browser  runs  under  the wm(1) window manager, or directly on the
       draw(3) and cons(3) devices.  When charon starts, it checks to  see  if
       wm  is  running;	 if  it is then charon creates a new wm window for its
       display, otherwise it uses the whole area of the display device.

       Charon implements an image cache to help reduce the overhead of	revis‐
       iting  pages.   The image cache resides in memory for the duration of a
       session.	 The cache is managed by discarding least recently used images
       once  the  cache	 bounds have been reached.  Currently, charon does not
       provide a general purpose web cache; all other  resources  have	to  be
       reloaded when needed.

   Navigation
       Charon  provides	 navigation controls familiar to any web-surfer: back,
       forward, reload, home, stop and URL  entry.   Navigation	 of  web-based
       information is by means of following HTML links, this is done by click‐
       ing on them using mouse button-1, or the touch-screen.  Clicking	 mouse
       button-2	 on  a	link  causes its address to be displayed in the status
       line of charon's display.  Navigation to other information is  achieved
       by  clicking  on	 the  URL  entry  field	 and typing the address of the
       resource, followed by the Enter key.

       The retrieval and processing of the current page is immediately	termi‐
       nated by clicking the Stop button.

       As  resources  are  browsed, a history of their web addresses (URLs) is
       built up.  At any time you can navigate forwards and backwards  through
       this  list  using the Forward and Back buttons.	Additionally, clicking
       the History button, displays the entire history list as a set of	 links
       enabling the user to quickly jump to any position in the list.

       Sometimes,  it  is  not possible to retrieve all of the components of a
       web document at the time that it is requested.  Often this  is  because
       the  remote  server  is very busy or not available.  This can result in
       the presentation of the document being incomplete  or  even  corrupted.
       Clicking	 the  Reload  button  causes charon to attempt to retrieve the
       current document and all of its components again.

       Charon displays a progress panel to indicate  the  download  status  of
       each  of the components of the current document.	 The progress panel is
       displayed at the bottom of the charon window.  Each  component  of  the
       current	document is represented by a rectangular block in the progress
       panel.  As the download of a component  progresses,  its	 corresponding
       block  is gradually filled in.  If an error occurs while downloading or
       processing the component, its block is  coloured	 red.	The  component
       address	and  amount downloaded, or reason for failure, can be obtained
       by clicking mouse button-1 on its progress block.

   Web Standards
       Standards are the life-blood of the World-Wide-Web; without  them,  the
       web  could  not	exist.	 Web  standards are under constant review with
       revised editions and complete new standards being published all of  the
       time.  This section lists the standards supported by charon at the time
       of writing this manual entry.  The version of the standard is given, if
       appropriate, alongside any comments on its implementation.

       Protocols      HTTP versions 1.0 and 1.1

		      HTTPS:  SSL  Protocol  versions  2.0  and 3.0.  X.509.v3
		      server certificates.

		      FTP: charon supports retrieval of plain text files only,
		      directory listings are not generated.

		      FILE:  Charon  attempts  to determine the file type by a
		      combination of the filename extension and examination of
		      the first few bytes of the file.	Directory listings are
		      not generated.

       HTML	      It is intended that charon supports  HTML	 version  3.2,
		      but  in  reality	there  is  no single standard!	Charon
		      attempts to be as close as possible to Netscape  Naviga‐
		      tor  Version  3 in terms of its markup support.  Obvious
		      bugs in Navigator 3 and the Netscape security model have
		      not been adopted.

       JavaScript     Charon  implements  ECMAscript-262 2nd Edition, which is
		      roughly equivalent to JavaScript1.1.  The ECMA-262 stan‐
		      dard  does  not define the host objects and classes that
		      should implemented by the	 browser.   Charon  implements
		      the  set of host objects and classes of Netscape Naviga‐
		      tor version 3.

       Encodings      US_Ascii, ISO_8859_1, UTF_8, Unicode (big-endian)

       Images	      GIF87a and GIF89a - animated GIFs always loop.
		      JPEG, XBitmap, Inferno BIT image(6) format.

   Configuration
       While using charon, a sub-set of the configuration options can be modi‐
       fied.   Clicking	 the Configuration button displays a config popup win‐
       dow, enabling the user to modify the current values  of	the  available
       options.

       The  full  set  of configuration options can be modified on the command
       line or in a configuration file.	 Comand	 line  options	are  processed
       after  the  configuration  file.	 The configuration file is loaded from
       /usr/user/charon/config where user is  obtained	by  reading  the  file
       /dev/user.   If	this  file  does  not  exist,  the file /services/con‐
       fig/charon.cfg is read instead.	Options are processed in  order;  some
       options	override settings affected by others and so the order in which
       they are used is important.

       Options are specified using a key, value pair.	On  the	 command  line
       this takes the form:

	      -key value

       Where  -key  and	 value	are  individual	 items in the argument list to
       charon.

       In the config file options take the form:

	      key=value

       Where value is the remainder of the input line after the `=' character.
       Any  text  lines in the config file that start with a `#' character are
       ignored as comment lines.

OPTIONS
       userdir
	      The directory where charon expects  to  find  its	 configuration
	      files  such as, bookmark and cookie files.  The default value is
	      /usr/user/charon/ where user is obtained	by  reading  the  file
	      /dev/user.

       starturl
	      Specifies	 the  URL  of  the  first  document to be displayed by
	      charon at startup.  The default value  is	 file://localhost/ser‐
	      vices/webget/start.html

       homeurl
	      Specifies the URL of the document to retrieve when the Home but‐
	      ton is  clicked.	 The  homeurl  can  only  be  changed  if  the
	      change_homeurl  option is enabled.  Setting homeurl also set the
	      value  of	 the  starturl	 option.    The	  default   value   is
	      file://localhost/services/webget/start.html

       change_homeurl
	      Enables  editing of the Home URL in the configuration popup win‐
	      dow.  A non-zero integer value enables this  option,  all	 other
	      values  disable  it This option also enables the homeurl option.
	      The default value is 1.

       helpurl
	      Specifies the URL of the document to retrieve when the Help but‐
	      ton  is  clicked.	  The  default	value is file://localhost/ser‐
	      vices/webget/help.html

       httpproxy
	      Specifies the host name and port of a  web  proxy	 server.   The
	      address  is  given in the form of a URL, where the optional port
	      number can be specified after the server name by separating them
	      by a colon `:'.  The default value is the empty string, specify‐
	      ing that no web proxy server should be used.

       noproxy or noproxydoms
	      Specifies a list of network domains for which a web proxy should
	      not  be used.  The domains in the list can be separated by semi‐
	      colon, comma, space or tab characters.  The default value is the
	      empty list.

       usessl Extends  SSL  support.   Accepted	 values are ``v2'' and ``v3''.
	      Initially SSL support is configured off.	Enabling version 1  or
	      version  2  support  restricts SSL support to that specific ver‐
	      sion.  Specifying the  option  twice,  once  with	 each  of  the
	      options,	enables	 dual  version	SSL support whereby the remote
	      server is probed to determine which version it  supports.	  Some
	      servers  only  support  one of the versions and may not tolerate
	      the special version2/3 probe.

       buttons
	      Specifies the set of buttons that appear on the  window  manager
	      title-bar.  The buttons are given as a list of button names sep‐
	      arated by comma, space or tab characters.	  Valid	 button	 names
	      are help, resize and hide.  The default value is for all buttons
	      to be displayed.

       defaultwidth or width
	      Set the initial window width.  This option  is  only  meaningful
	      when  running  under the window manager.	If the specified width
	      exceeds the screen width then the screen	width  is  used.   The
	      default value is 630.

       defaultheight or height
	      Set  the initial height of the main display panel, this does not
	      include the height of the control	 and  progress	panels.	  This
	      option is only meaningful when running under the window manager.
	      If the total height of the  charon  window  exceeds  the	screen
	      height,  the  main  display panel height will be reduced to fit.
	      The default value is 450.

       x and/or y
	      Set the initial window position.	These options are  only	 mean‐
	      ingful when running under the window manager.  The default value
	      for both options is 0.

       imagelvl
	      Specify how to handle image  components  of  a  document.	  This
	      option  takes  a numeric argument.  A value of 0 prevents images
	      from being downloaded or displayed.  A value of 1 will  download
	      and  display  images but not animate GIFS - only the first frame
	      of an animated GIF will be displayed.  A	value  of  2  or  more
	      enables  full  image processing.	The default value enables full
	      image processing.

       imagecachenum
	      Specify the maximum number of images that can remain resident in
	      the image cache.	The default value is 60.

       imagecachemem
	      Specify  the  maximum  amount  of	 image memory available to the
	      image cache in bytes.  The cache is managed  such	 that  neither
	      the  imagecachenum  nor  imagecachemem limits are exceeded.  The
	      image cache tries to ensure that no more than 80%	 of  available
	      system  image  memory is taken by the cache, irrespective of the
	      value of this option.  The default value is 80%  of  the	system
	      image memory that was available when charon was started.

       docookies
	      Enable cookie handling.  A non-zero numeric value enables cookie
	      handling, all other values disable  it.	The  cookie  cache  is
	      maintained  in  the  cookies file in the userdir directory.  The
	      default value is 0, cookie handling disabled.

       doscripts
	      Enable JavaScript support.  A  non-zero  numeric	value  enables
	      JavaScript,  all	other values disable it.  The default value is
	      0, JavaScript processing disabled.

       showprogress
	      A non-zero numeric value results in  the	progress  panel	 being
	      displayed.   All	other  values hide the progress panel, leaving
	      more vertical space for the  main	 display  area.	  The  default
	      value is 1, causing the progress panel to be displayed

       http   Set  the	version	 of  HTTP  to  use when communicating with web
	      servers.	Supported versions are 1.0 and 1.1.  Any  value	 other
	      than  1.1	 results  in HTTP1.0 being used.  The default value is
	      1.0.

       nthreads
	      Specifies the maximum number of concurrent downloads of document
	      components.   Generally,	if  this  number is higher, pages will
	      complete faster as charon will not have to wait for the download
	      of one component to complete before another can be started.  The
	      downside is that a higher number of  concurrent  downloads  will
	      use  more memory during the download process.  The default value
	      is 4.

FILES
       /services/config/charon.cfg
	      The default configuration file.

       userdir/config
	      The user specific configuration file.  userdir is given  by  the
	      value of the userdir option.

       userdir/cookies
	      The  cookie cache.  userdir is given by the value of the userdir
	      option.

       /services/webget/start.html
	      The default start page.

       /services/webget/help.html
	      The default help page.

SOURCE
       /appl/charon/
	      The main charon source files.

       /appl/lib/ecmascript/
	      Javascript (ECMA-262) implementation.

BUGS
       Charon has more than its fair share of real bugs.  The  following  list
       documents the problems that are most likely to be encountered.

       Charon  implements  its	table layout as per the algorithm described in
       rfc1942.	 This sometimes results in table-based	documents  being  laid
       out differently to other browsers.

       JavaScript  is  a source of many problems.  Many scripts do not specify
       the language version they employ.  Additionally different language ver‐
       sions  and  browsers imply a different set of host objects and classes.
       Such differences often give rise to syntax or  null  reference  errors.
       This  whole  situation  places  a  great burden on the script author to
       write safe and compliant	 scripts;  unfortunately  authors  are	rarely
       aware of this burden!

       The following elements of JavaScript1.1 are not fully implemented:

       Document.applets,  Document.embeds  and	Document.plugins: Java Applets
       are not supported, the arrays are always empty.

       Document.onunload: The property exists and can be assigned to, but  the
       event is never raised.

       Window.open():  A new window is never opened. If a URL is specified for
       the new window, the current document will be replaced with that of  the
       new URL.

       Other annoyances include:

       Window resize forces a complete document reload.

       Frames in a frameset are processed one at a time, not concurrently.

       It  is  not possible to save downloaded data to file.  This is particu‐
       larly annoying for MIME types that charon does not support.

       The history list can get confused, especially when following  links  in
       framesets before the complete frameset has been downloaded.

								     CHARON(1)
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