This ECMAScript extracts the filename from a URL. eg. the filename 'index4.svg' would be extracted from the document.URL with the value 'http://rorbuilder.info/r/whiteboardqueue/index4.svg'.

var regexp = /(\w|[-.])+$/
str = document.URL
a = regexp.exec(str)
alert(a[0])

Reference: Regular Expressions: Methods - Doc JavaScript [webreference.com]

This example will show you how to escape and un-escape a value to be included in a URI and within HTML.

require 'cgi'

# escape
name = "ruby?"
value = "yes"
url = "http://example.com/?" + CGI.escape(name) + '=' + CGI.escape(value) + "&var=T"
# url: http://example.com/?ruby%3F=yes&var=T
html = %(<a href="#{CGI.escapeHTML(url)}">example</a>)
# html: <a href="http://example.com/?ruby%3F=yes&amp;var=T">example</a>

# unescape
name_encoded = html.match(/http:([^"]+)/)[0]
# name_encoded: http://example.com/?ruby%3F=yes&amp;var=T
href = CGI.unescapeHTML(name_encoded)
# href: http://example.com/?ruby%3F=yes&var=T
query = href.match(/\?(.*)$/)[1]
# query: ruby%3F=yes&var=T
pairs = query.split('&')
# pairs: ["ruby%3F=yes", "var=T"]
name, value = pairs[0].split('=').map{|v| CGI.unescape(v)}
# name, value: ["ruby?", "yes"]

This Ruby code generates shortened URLs. It has the added feature that it will not allow words to be created accidentally eg. swear words.

#!/usr/bin/ruby

class ShortUrl
  def initialize()
    @chars = ('a'..'z').to_a + ('1'..'9').to_a + ('A'..'Z').to_a
    @array_size = @chars.size
    @h = Hash.new
    @chars.each {|c| @h[c] = '0'}
    vowels = %w(a e i o u A E I O U 4 3 1 0)
    vowels.each {|v| @h[v] = '1'}
    nums = %w(2 5 6 7 8 9)
    nums.each {|n| @h[n] = '2'}
    @count = 0
    @a = Array.new(7, -1)
    @k = 0
  end 

  def iterate_chars(array_size)
    (0..array_size).each {|i| 
      increment_index(@k)
      convert_to_chars()
    }
  end
  
  def convert_to_chars()
    buffer = ''
    @a.each {|i|
      buffer << @chars[i] if i >= 0
    }
    a = buffer.reverse.scan(/./)
    k = a.length  
    if  (k > 1)  
      if ((@h[a[k-2]] + @h[a[k-1]]) != '10')
        puts buffer.reverse 
      end
    else
      puts buffer.reverse
    end
  end

  def get_short_url(count)
    if count >  @array_size
      new_count = count - @array_size
      iterate_chars(@array_size)
      get_short_url(new_count)
    else
      iterate_chars(count)
    end
  end
  
  def increment_a(i)
    if @a[i] < @array_size - 1
      @a[i] = @a[i] + 1
      return i 
    else
      @a[i] = 0
      return i += 1
    end 
  end

  def increment_index(k)
    old_k = k
    k = increment_a(k)
    
    if k != old_k
      increment_index(k)
    else
      k = 0
    end
    k
  end

end

if __FILE__ == $0
  su = ShortUrl.new  
  su.get_short_url(222761)
end

Note: You will most likely see the " `convert_to_chars': stack level too deep (SystemStackError)" error message after around 253950 iterations, I'm presuming this is expected due to the memory constraints of the language. However 253k short urls is enough for linking my website to itself.

This is a workaround to get spaces in URL as pluses not %20 like it is in Rails2.

module ActionController::Routing
  class DynamicSegment
    def interpolation_chunk
      "\#{CGI.escape(#{local_name}.to_s)}"
    end

    def match_extraction(next_capture)
      default_value = default ? default.inspect : nil
      %[
        value = if (m = match[#{next_capture}])
          CGI.unescape(m)
        else
          #{default_value}
        end
        params[:#{key}] = value if value
      ]
    end
  end
end

This code will read a text file using Apache then upon a user request, look for a url containing /l/ eg. http://mysite.com/l/digg and rewrite the URL in full eg. http://mysite.com/gwd/feed/digg.html . The example file is shown here for completeness.

RewriteMap uses a text file as a convenient alternative for the administrator when declaring many rewrite rules. Code based on the article from ONLamp.com - A Day in the Life of #Apache http://urltea.com/1vwb

<file name="links.txt" location="/var/www/localhost/">
scotsman /gwd/feed/scotsman.html
digg /gwd/feed/digg.html
</file>

<IfModule mod_rewrite.c>
RewriteEngine on
RewriteMap links txt:/var/www/localhost/links.txt
RewriteRule ^/l/(.*) ${links:$1|http://mysite.com/} [R]
</IfModule>

Note: The [R] at the end of RewriteRule means redirect, to have a clean url simply remove that switch.

*update 15-Feb-08 *
Restart Apache rather reloading the module when switching redirection on or off for a RewriteRule. The Apache version 2.2.6 (Unix) didn't pick up my settings correctly when I tried /etc/init.d/apache2 reload, instead I needed to use /etc/init.d/apache2 restart.

Rewrite a long url as a short easy to remember url with mod_rewrite. Place this code in httpd.conf or the virtual hosts file. Original code from sitepoint - mod_rewrite: A Beginner's Guide to URL Rewriting http://urltea.com/1v6d .

<IfModule mod_rewrite.c>
RewriteEngine on
RewriteRule ^/shortcut$ /complicated/and/way/too/long/url/here
</IfModule>

this method returns string, which is perfect for SEO-friendly URLs.

features:
- converts every improper character to a hyphen
- returns a lowercase string

I POSTED AN EVEN BETTER METHOD ON MY BLOG: http://tinyurl.com/2vurbq

def create_callname (title)
	title.downcase.gsub(/[^a-z0-9]+/i, '-')
end

No regexes, allows URLs with ports or IPs. Inspiration from here

  validates_each :href, :on => :create do |record, attr, value|
    begin
      uri = URI.parse(value)
      if uri.class != URI::HTTP
        record.errors.add(attr, 'Only HTTP protocol addresses can be used')
      end
    rescue URI::InvalidURIError
      record.errors.add(attr, 'The format of the url is not valid.')
    end
  end

// description of your code here
This code reads an xml file, modifys an element and saves the file locally.

require 'net/http'
require 'rexml/document'

url = 'http://www.example.com/journal080907.xml'

element_name = ARGV[0] # basic_category
xpath = ARGV[1] # eg.'entries/entry'
file = ARGV[2] # eg. 'journal080907.xml'
element_value = ARGV[3] # 'ruby'

file = File.new(file,'w')
# get the XML data as a string
xml_data = Net::HTTP.get_response(URI.parse(url)).body

# extract event information
doc = REXML::Document.new(xml_data)
docx = doc

node = docx.elements[xpath]
element = node.elements[element_name]
puts element.text
element.text = 'ruby'
file.puts docx

// description of your code here

#include <windows.h>
#include <httpfilt.h>

#define MAX_URL_LEN 4096

BOOL WINAPI GetFilterVersion(HTTP_FILTER_VERSION * pVer)
{
      pVer->dwFlags = (SF_NOTIFY_SECURE_PORT | SF_NOTIFY_NONSECURE_PORT | SF_NOTIFY_PREPROC_HEADERS | SF_NOTIFY_ORDER_HIGH);
      pVer->dwFilterVersion = HTTP_FILTER_REVISION;
      strcpy_s(pVer->lpszFilterDesc,9,"Blah blah blah");
      return TRUE;
}

void ReMapURLs(CHAR* pUrl,HTTP_FILTER_CONTEXT* pfc,PHTTP_FILTER_PREPROC_HEADERS pHeaders)
{
      if (pUrl[0] != '/') return;

      CHAR *iUrl = 0;
      BOOL doSet = FALSE;

      char *sOldUrls[] = { "/test/", "/TEST/" };
      char *sNewUrls[] = { "/go/", "/GO/" };

      for (int i=0; i<2; i++)
      {
            if (iUrl = strstr(pUrl,sOldUrls[i]))
            {
                  doSet = TRUE;
                  memcpy(iUrl,sNewUrls[i],strlen(sNewUrls[i]));
            }
      }

      if (doSet) pHeaders->SetHeader(pfc, "url", pUrl);
}

DWORD WINAPI HttpFilterProc(HTTP_FILTER_CONTEXT *pfc,DWORD NotificationType,VOID * pvData)
{
      PHTTP_FILTER_PREPROC_HEADERS pHeaders;
      DWORD cUrlOrig = MAX_URL_LEN;
      DWORD cUrl = cUrlOrig;
      CHAR rgUrl[MAX_URL_LEN];
      CHAR *pUrl;
      BOOL result;

      switch ( NotificationType )
      {
            case SF_NOTIFY_PREPROC_HEADERS:
                  pHeaders = (PHTTP_FILTER_PREPROC_HEADERS) pvData;
                  result = pHeaders->GetHeader(pfc, "url", rgUrl, &cUrl);

                  if (!result && cUrl > cUrlOrig)
                  {
                        pUrl = (CHAR*)LocalAlloc(0, cUrl);
                        result = pHeaders->GetHeader(pfc, "url", pUrl, &cUrl);
                        if (!result)
                        {
                              LocalFree(pUrl);
                              break;
                        }
                        ReMapURLs(pUrl, pfc, pHeaders);
                        LocalFree(pUrl);
                  }
                  else
                        ReMapURLs(rgUrl, pfc, pHeaders);
                  break;
            default:
                  break;
      }
      return SF_STATUS_REQ_NEXT_NOTIFICATION;
}