Example recipes
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## 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.

### Tip

The “URI rewriting” feature of ELinks handles many of the same tasks as the Lua hook shown here, and you can conveniently configure it via the option manager. It is not quite as versatile, though.

    function match (prefix, url)
        return string.sub (url, 1, string.len (prefix)) == prefix
    end

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

    function plusify (str)
        return string.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 (string.sub (url, 4)))
            return "http://www.google.com/search?q="..url.."&btnG=Google+Search"

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

        -- Dictionary.com search (e.g. ,dict congenial).
        elseif match (",dict", url) then
            url = plusify (strip (string.sub (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 (string.sub (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 (string.sub (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?IDV10450.txt"

        -- Unmatched
        else
            return url
        end
    end

### 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.

    function goto_url_hook (url, current_url)
                    .
                    .

        -- Expand ~ to home directories.
        elseif match ("~", url) then
            if string.sub(url, 2, 2) == "/" then    -- ~/foo
                return os.getenv ("HOME")..string.sub(url, 2)
            else                                    -- ~foo/bar
                return "/home/"..string.sub(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 for the web site.

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 string.find (no metacharacters)
    function sstrfind (s, pattern)
        return string.find (s, pattern, 1, true)
    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 = string.gsub (html, '<TABLE CELLSPACING="0".-</TABLE>', '', 1)
                html = string.gsub (html, '<TR BGCOLOR="#FFF.-</TR></TABLE>', '', 1)
            else
                html = string.gsub (html, 'WIDTH="120">\n<TR.+</TABLE></TD>', '>', 1)
            end
            html = string.gsub (html, '<A HREF="http://www.internet.com.-</A>', '')
            html = string.gsub (html, "<IFRAME.-</IFRAME>", "")
            -- emphasis in text is lost
            return string.gsub (html, 'text="#002244"', 'text="#001133"', 1)
        end

        return nil
    end

#### linuxgames.com

### Note

This recipe is out of date for the web site.

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

    function pre_format_html_hook (url, html)
                    .
                    .

        elseif string.find (url, "linuxgames.com", 1, true) then
            return string.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.

### Warning

This recipe opens a temporary file insecurely.

    function pre_format_html_hook (url, html)
                    .
                    .

        -- Handle gzip'd files within reasonable size.
        if string.find (url, "%.gz$") and string.len (html) < 65536 then
            local name = tmpname ()
            local file = io.open (name, "wb")
            file:write (html)
            file:close ()
            html = pipe_read ("(gzip -dc "..name.." || cat "..name..") 2>/dev/null")
            os.remove (name)
            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`.)

### Note

The `io.popen` function is not available on all platforms.

    function pipe_formatted_to (program)
        local lp, errmsg = io.popen (program, "w")
        if lp == nil then
            error (errmsg)
        else
            lp:write (current_document_formatted (79))
            lp:close ()
        end
    end

    -- Send the current document to `lpr'.
    function lpr ()
        pipe_formatted_to ("lpr")
    end

    -- Send the current document to `enscript'.
    function enscript ()
        pipe_formatted_to ("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.

### Tip

You can also use the built-in “URI passing” feature for this.

    -- 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 Hierarchical 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.

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