Thursday, June 26, 2008

Lynx HTTP EXTERNAL Menu Script

One thing keeping my friend Larry from getting the most out of my usnatch program and Lynx externals is awkwardness he has in dealing with the EXTERNAL selection menus. He is blind and this coupled with many of the long, complex URLs, (in many cases having stretches of random hash characters) that are passed to the Lynx EXTERNAL menu for special handling make it hard for him to seperate out the choices the menu presents. He literally can't wade through the URLs to get to the menu selection options. This is different from many of the other Lynx menus, where simple brief descriptions of the choices are given, without interjecting the names of temporary files and such into the options to confuse the issues.

To try and deal with this problem, I present a bash script below to replace a collection of Lynx EXTERNAL entries for http with a single entry, that presents a simplified menu. This whole idea is a variation on what I documented in my article Lynx/Kermit Coordination Part I hosted by the Kermit Center at Columbia Univesity. This script will have to be customized, and a seperate one would have to be created for other protocols such as ftp, ssh, irc and such. I've put extensive notes in this script, since I think it makes explination simpler if the notes are close to the subject instead of before or after in this blog's narrative. Also, the people using it might not be familiar with bash, so I try to explain as much as I can, so they can knowledgably change it to their needs.

To install this script, first make sure your version works from the command promt. Then comment out all the


statements in your lynx.cfg file, both any in your home directory, and those in /etc/ and it's subdirectories, adjust the script to include those possibilities you want in it, and put a single EXTERNAL statement: %s:TRUE

Where is taken to be the name of the menu script.

I've put a copy of this script online at a Yahoo group for Larry's friends,

#! /usr/bin/env bash
#  #!/usr/bin/bash  -

#  '#! /', env per
#  'bash Cookbook', 1st edition, recipe #15.1, p. 321
#  "Finding bash Portably for #!"
#  trailing '-' per
#  'bash Cookbook', 1st edition, recipe #14.2, p. 283
#  "Avoiding Interpreter Spoofing"

#  the first line convention points to the intepretor to be used.

#  Some bash conventions for beginners:
#  hash/pound/sharp/octhorps to the end of line are comments.
#  Lines ending exactly with a backslash, '\', are continued
#  with the next line.
#  Trailing whitespace after the backslash can cause errors,
#  so beware of it.
#  I urge you to look up aspects of this script,
#  either with man bash, or if you are running bash
#  at your command prompt, with the help command
#  such as 'help case' or 'help select'.

URL="${1}"  ;

PS3='What EXTERNAL action do you want? '
#         -- defaults to '#?'
#            trailing blank desirable for spacing of response
#            from prompt
#            PS3 is the Select Menu Loop prompt in bash

#  Note 'for' statement like syntax of select:

select external_action in       \
      'Quit externals                                              '          \
      'Print the URL'           \
      'USnatch'                 \
      'lynxvt'                  \
      'screened-lynx'           \
      'javascript-links2'       \
      'graphical-links2'        \
      'W3M'                     \
      'links'                   \
      'elinks'                  \
      'Blogspotviewer'          \
      'lynx-noreferer'          \
      'lynx-nofilereferer'      \
      'Privoxy Control Panel'   \
      'Microbookmarker'         \
      'wget'                    \
      'Bug-Me-Not'              \
      'whomis'                  \
      'nspeep'                  \
      'pingvolley'              \
      'lynxtab'                 \
      'lynxtab-blank'           \
      'lynx-blank'              \
      'frys'                    \

#    Note: the last select menu item should not and a trailing
#    '\' to continue on to the next line.
#    I've placed each menu item or quoted phrase on a seperate
#    continuation line.
#    At this point, it is normally desirable to have one menu item
#    for each of the case statement stanza's below.
#    They don't need to be in order.
#    There just has to be a menu prompt item
#    and a case "whatever )" that match
#    so the case stanza can be triggered.
#    Be careful in using '*' 'splat' patterns,
#    that you do not unintentionally match more than
#    the desired pattern by mistake.
#    This could accidently short circuit desired action,
#    keeping a case stanze from being taken when wanted,
#    and causing another to be taken instead.
#    If all the menu items are short, select will try to put
#    them in multiple columns.
#    Only one item needs to be wide, (which can be because of trailing
#    blanks) to trigger single column menu display.
#    In this case, I used the 'Quit' item to do this with,
#    since it is basicly matched for the most part with a '*'
#    keeping the line in the case statement a reasonable length.
#    The menu items are only needed to clue the user on the
#    significance of each number chosen,
#    and to tie that to the case stanza.
#    Alternatively, you can keep the menu items in a strict order,
#    and use 'REPLY' for the case variable, in which case
#    each case stanza would be picked on the basis of the
#    number selected from the menus instead of patterns
#    that match the menu item strings.
#    In this case, ordering is critical.

#    Many of these actions are special purpose scripts I have
#    written and are included here just to provide a realistic
#    example.
#    The size is probably excessive for some people.
#    This script will certainly have to be customized to your
#    personal needs.


  case ${external_action} in

  #  item between 'case' and 'in' undergoes
  #  several levels of evaluation before
  #  the case statement is finally executed.

  #  Case stanza's start with
  #  string_to_match )
  #  list of actions ;
  #  break  ;   # include a break statement to break out of the
  #             # select menu loop
  #  ;;    #  double semicolons  end actions and stanza

  Q* )
    echo 'Returning to browsing'  ;
    break  ;
    #  Thumb rule in this sort of script is
    #  that a break is needed whenever there
    #  is no exec statement in a case stanza.
    #  This stops the select loop after a decisive action.

  P* )
    read -p "The URL in question: ${URL} "  TRASH  ;
    break  ;

  USnatch )
    exec    usnatch  ${URL}  -i -p  ;
    #  break is not needed after an exec statement
    #  because this script's process, including
    #  the select loop is replaced
    #  by the action of the exec statement,
    #  ending the select loop.
    #  You could put a break after each exec,
    #  it would probably be excessively cautious,
    #  since it would only be executed under bizarre conditions.

  lynxvt )
    #  exec    lynxvt  ${URL}  &  ;
    exec    lynxvt  ${URL}    ;

  screened-lynx )
    screen -t 'lynx ...' lynx   \
        -useragent='Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)'  \
        ${URL}    ;
    break  ;

  javascript-links2 )
    screen -t 'jlinks'  \
        links2 -enable-javascript 1 -html-numbered-links 1  \
        ${URL}    ;
    break  ;

  graphical-links2 )
    sudo links2 -g -driver svgalib -mode 640x480x256   \
        -enable-javascript 1 -html-numbered-links 1    \
        ${URL}    ;
    break  ;

  lynx-noreferer )
    exec  lynx -noreferer=off -tna ${URL}    ;

#    start of a typical case stanza:
  lynx-nofilereferer )
    exec  lynx -nofilreferer=off -noreferer=off -tna ${URL}  ;
# end of the typical case stanza

  Privoxy* )
    screen -t 'Privoxy Control Panel'   \
      lynx -nofilereferer=off -noreferer=off  \
      -tna 'http\://'   ;
    break  ;

  Microbookmarker )
    exec  microBkMrk ${URL}  ;

  Blogspotviewer )
    exec  blogspoter ${URL}  ;

  [Ww]3[Mm] )
    exec  w3m ${URL}  ;

  links )
    exec  links ${URL}  ;

  elinks )
    exec  elinks ${URL}  ;

  wget )
    exec  nohup wget  --background -a ~/wget.log -P /mnt/hda8/  ${URL}  ;

  Bug-Me-Not )
    screen -t Bug-Me-Not   \
       lynx -cookies${URL}  ;
    break  ;

  whomis )
    exec  whomis  ${URL}  ;

  nspeep )
    exec  nspeep  ${URL}  ;

  pingvolley )
    exec  pingvolley  ${URL}  ;

  lynxtab )
    exec  lynxtab  ${URL}  ;

  lynxtab-blank )
    exec  lynxtab    ;

   lynx-blank )
    exec  env -u HTTPS_PROXY='' lynx -tna -accept_all_cookies    ${URL}  ;

  frys )
    #  to send pdf's straight to a printer
    #  this script has mainly been used for Fry's Electronics
    #  online version of their newspaper ads.
    exec  lprfrys  ${URL}  ;

  bash )
    #  this is just to explore the environment that the
    #  externals run in
    exec  bash -i  ;

  * )
    # if something unexpected happens,
    # this catchall stanza should simply end the script.
    # '*' matches anything at all, after all other
    # patterns have been given a chance to match.
    # it is customary to include this
    # at the end of bash case statements.
    break  ;

  esac     #  'case' backwards marks the end of the case statement

done       #  this done statement marks the end of the select menu loop

exit  ;  #  just to make sure!  :-)

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