Example recipes

This chapter contains some example scripts that you can use. All of them come from contrib/lua/hooks.lua. I really recommend you to see it directly instead of copying code out of this document. Also, not everything in there is covered here.

If you would like to contribute scripts, that would be great! Please send them to me at tjaden@users.sourceforge.net. Cliff and I plan to start a script repository, provided we get some contributions. As for script ideas, you'll just have to be a little creative :-)

Also take a look at the contrib/lua/ directory in the ELinks distribution. Note that Peter and Cliff don't maintain the Lua support intensively anymore, thus it would be probably nice to Cc me (pasky@ucw.cz) if you want to contribute some patch, so that I would be able to add it to the ELinks distribution.

Go to URL on steroids

There are some web sites that I visit often. Bookmarks are okay, but they are separate from the "Go to URL" dialog box, so I keep forgetting to use them. Also, when I visit a search engine home page, all I really want to do is enter a search term.

The following script allows me to type certain strings into the "Go to URL" dialog box, and it will convert them to the URL I actually want to visit. As a bonus, it allows me perform some searches on sites like Google without loading up the front page first.

function match (prefix, url)
    return strsub (url, 1, strlen (prefix)) == prefix
end

function strip (str)
    return gsub (str, "^%s*(.-)%s*$", "%1")
end

function plusify (str)
    return gsub (str, "%s", "+")
end

function goto_url_hook (url, current_url)
    -- Google search (e.g. ,gg unix browsers).
    if match (",gg", url) then
        url = plusify (strip (strsub (url, 4)))
        return "http://www.google.com/search?q="..url.."&btnG=Google+Search"

    -- Freshmeat search.
    elseif match (",fm", url) then
        url = plusify (strip (strsub (url, 4)))
        return "http://www.freshmeat.net/search/?q="..url

    -- Appwatch search (e.g. ,aw lynx).
    elseif match (",aw", url) then
        url = plusify (strip (strsub (url, 4)))
        return "http://www.appwatch.com/Linux/Users/find?q="..url

    -- Dictionary.com search (e.g. ,dict congenial).
    elseif match (",dict", url) then
        url = plusify (strip (strsub (url, 6)))
        return "http://www.dictionary.com/cgi-bin/dict.pl?db=%2A&term="..url

    -- RPM search (e.g. ,rpm links).
    elseif match (",rpm", url) then
        url = plusify (strip (strsub (url, 5)))
        return "http://www.rpmfind.net/linux/rpm2html/search.php?query="
                ..url.."&submit=Search+..."

    -- Netcraft.com search (e.g. ,whatis www.google.com).
    elseif match (",whatis", url) then
        url = plusify (strip (strsub (url, 8)))
        return "http://uptime.netcraft.com/up/graph/?host="..url

    -- LinuxToday home page.
    elseif match (",lt", url) then
        return "http://linuxtoday.com/"

    -- Weather forecast for Melbourne, Australia.
    elseif match (",forecast", url) then
        return "http://www.bom.gov.au/cgi-bin/wrap_fwo.pl?IDF02V00.txt"

    -- Unmatched
    else
        return url
    end
end

(Note that this was noticably enhanced and rewritten in the ELinks standart hooks.)

Expanding ~ (tilde)

By adding an extra snippet of code to the previous example, we can make ELinks expand pathnames such as ~/foo/bar and ~user/zappo, like in the shell and other Unix programs.

-- Home directory: If you do not enable system functions, you will need
-- to set the following to your home directory.

home_dir = (getenv and getenv ("HOME")) or "/home/MYSELF"

function goto_url_hook (url, current_url)
                .
                .

    -- Expand ~ to home directories.
    elseif match ("~", url) then
        if strsub(url, 2, 2) == "/" then    -- ~/foo
            return home_dir..strsub(url, 2)
        else                                -- ~foo/bar
            return "/home/"..strsub(url, 2)
        end

                .
                .

Filtering crap

Many web pages nowadays have columns to the left and right of the text, which are utterly useless. If you happen to be viewing the page in a 80x25 screen, the text you want to read ends up crammed into a tiny space in the centre. We use ELinks Lua support to manipulate the HTML before it reaches the parser.

linuxtoday.com

Note: This recipe is out of date.

Linux Today has two problems when viewed in ELinks: the useless columns on the left and the right and all the text appears in cyan. Here is a quick recipe to fix that:

-- Plain strfind (no metacharacters)
function sstrfind (s, pattern)
    return strfind (s, pattern, 1, 1)
end

function pre_format_html_hook (url, html)
    -- Strip the left and right columns from Linux Today pages
    -- and change the font colour to white.
    if sstrfind (url, "linuxtoday.com") then
        if sstrfind (url, "news_story") then
            html = gsub (html, '<TABLE CELLSPACING="0".-</TABLE>', '', 1)
            html = gsub (html, '<TR BGCOLOR="#FFF.-</TR></TABLE>', '', 1)
        else
            html = gsub (html, 'WIDTH="120">\n<TR.+</TABLE></TD>', '>', 1)
        end
        html = gsub (html, '<A HREF="http://www.internet.com.-</A>', '')
        html = gsub (html, "<IFRAME.-</IFRAME>", "")
        -- emphasis in text is lost
        return gsub (html, 'text="#002244"', 'text="#001133"', 1)
    end

    return nil
end

linuxgames.com

Here is a simpler example, for http://www.linuxgames.com/.

function pre_format_html_hook (url, html)
                .
                .

    elseif strfind (url, "linuxgames.com", 1, 1) then
        return gsub (html, "<CENTER>.-</center>", "", 1)

                .
                .

Reading gzipped files

Note: ELinks already supports gzipped files natively.

Sometimes documents come gzipped in order to save space, but then you need to uncompress them to read them with ELinks. Here is a recipe to handle gzipped files on a Unix system.

-- This script requires system functions.

function pre_format_html_hook (url, html)
                .
                .

    -- Handle gzip'd files within reasonable size.
    if strfind (url, "%.gz$") and strlen (html) < 65536 then
        local tmp = tmpname ()
        writeto (tmp) write (html) writeto ()
        html = pipe_read ("(gzip -dc "..tmp.." || cat "..tmp..") 2>/dev/null")
        remove (tmp)
        return html
    end

                .
                .

Printing

Printing a web page with ELinks usually involves quite a few steps: Save the current document onto disk. Run it through ELinks on the command-line (so it fits into 80 columns) to generate a plain text version. Remove the 80th column from the text version, as it will make printers wrap down to the next line. Finally, run the processed file through `lpr', then delete it.

The following functions allow you to print web pages directly from ELinks, using lpr' or `enscript'. Type `lpr() or enscript() in the Lua Console to run them. (In the hooks.lua, I have also made it so you can just type lpr or enscript.)

-- This script requires system functions.

function catto (output)
    writeto (output)
    write (current_document_formatted (79))
    writeto ()
end

-- Send the current document to `lpr'.
function lpr ()
    -- You must compile Lua with `popen' support for pipes to work.
    -- See `config' in the Lua distribution.
    catto ("|lpr")
end

-- Send the current document to `enscript'.
function enscript ()
    catto ("|enscript -fCourier8")
end

Deferring to Netscape

If you come across a brain-dead web page that is totally unreadable with ELinks, you'd probably want to open it with a graphical browser. The following function opens the current document in Netscape.

-- This function requires `execute', a system function.

-- When starting Netscape: Set to `nil' if you do not want
-- to open a new window for each document.
netscape_new_window = 1

-- Open current document in Netscape.
function netscape ()
    local new = netscape_new_window and ",new_window" or ""
    execute ("( netscape -remote 'openURL("..current_url ()..new..")'"
             .." || netscape '"..current_url ().."' ) 2>/dev/null &")
end

Alternative bookmark system

Many people would like to have a bookmark system with categories (note that ELinks already supports that, marketing name Hiearchical bookmarks), and also to be able to view them and search for them in an HTML page. I have written an alternative bookmark system (for ELinks), which some people may like better than the standard bookmark system.

More ideas

  • The Lua interface needs to be redesigned to provide more flexible, coherent and usable interface to the scripts.
  • Cliff Cunnington had a neat idea of clipping text that you see in web pages (you enter a regexp that will match the start and end of the text you want to clip), and saving the text to disk, along with the URL and timestamp. This would help if you find that you can't ever remember where you had seen a piece of text, or if you want to keep a piece of information but don't need to save the entire page.
  • People who use download management programs could write a function to send the current link to their favourite downloading program.
  • If you wrote a small C program to put text into the X11 selection clipboard, you could pass the current link or URL to that program, to make it easier to paste URLs into other windows. It might be possible to do the same with GPM, or the KDE/GNOME equivalents.
  • Send the current page to Babelfish for translation.
  • Look for stupid JavaScript URLs and convert them to something usable.
  • More things are possible, I'm sure. If you have an idea that requires another hook or function, contact me (Peter Wang) and I'll see what I can do.