Hack 31. Search for Special Characters

Search for the tilde and other special characters in URLs.

Google can find lots of different things, but at the time of this writing, it can't find special characters—except for $, recently added for use in number range searches ["Google Web Search Basics" and "Number Range" in Chapter 1]. That's a shame, because special characters can come in handy. The tilde (~), for example, denotes personal web pages.

This hack takes a query from a form, pulls results from Google, and filters the results for the presence of several different special characters in the URL, including the tilde.

Why would you want to do this? By altering this hack slightly (see the "Hacking the Hack" section), you could restrict your searches to just pages with a tilde in the URL, an easy way to find personal pages. Maybe you're looking for dynamically generated pages with a question mark (?) in the URL; you can't find these using Google by itself, but you can with this hack. And, of course, you can turn the hack inside-out and not return results containing ~, ?, or other special characters. In fact, this code is more of a beginning than an end unto itself: you can tweak it in several different ways to do several different things.

2.13.1. The Code

Save this code to a text file called aunt_tilde.cgi. Replace insert key here with your Google API key.

#!/usr/local/bin/perl

# aunt_tilde.pl

# Finding special characters in Google result URLs.

     

# Your Google API developer's key.

my $google_key='insert key here';

     

# Number of times to loop, retrieving 10 results at a time.

my $loops = 10;

     

# Location of the GoogleSearch WSDL file.

my $google_wdsl = "./GoogleSearch.wsdl";

     

use strict;

     

use CGI qw/:standard/;

use SOAP::Lite;

     

print

  header( ),

  start_html("Aunt Tilde"),

  h1("Aunt Tilde"),

  start_form(-method=>'GET'),

  'Query: ', textfield(-name=>'query'),

  br( ),

  'Characters to find: ', 

  checkbox_group(

    -name=>'characters', 

    -values=>[qw/ ~ @ ? ! /],

    -defaults=>[qw/ ~ /]

  ),

  br( ),

  submit(-name=>'submit', -value=>'Search'),

  end_form( ), p( );

     

if (param('query')) {

  

  # Create a regular expression to match preferred special characters.

  my $special_regex = '[\\' . join('\\', param('characters')) . ']';

     

  my $google_search  = SOAP::Lite->service("file:$google_wdsl");

     

  for (my $offset = 0; $offset <= $loops*10; $offset += 10) {

    my $results = $google_search -> 

      doGoogleSearch(

        $google_key, param('query'), $offset, 10, "false", "",  "false",

        "", "latin1", "latin1"

      );

     

    last unless @{$results->{resultElements}};

     

    foreach my $result (@{$results->{'resultElements'}}) {

     

      # Output only matched URLs, highlighting special characters in red

      my $url = $result->{URL};

      $url  =~ s!($special_regex)!<font color="red">$1</font>!g and

        print 

          p(

            b(a({href=>$result->{URL}},$result->{title}||'no title')), br( ),

            $url, br( ),

            i($result->{snippet}||'no snippet')

          );

    }

  }

     

  print end_html;

}

2.13.2. Running the Hack

Point your browser at the aunt_tilde.cgi CGI script, type a search query into the Query field, click the checkboxes next to the special characters you're after, and click the Search button.

2.13.3. Hacking the Hack

There are a couple of interesting ways to change this hack.

2.13.3.1 Choosing special characters

You can easily alter the list of special characters that you're interested in by changing one line in the script:

    -values=>[qw/ ~ @ ? ! /],

Simply add or remove special characters from the space-delimited list between the / (forward slash) characters. If, for example, you want to add & (ampersands) and z (why not?), while dropping ? (question marks), that line of code should be:

    -values=>[qw/ ~ @ ! 

& z

 /],

Don't forget those spaces between characters in the list.

2.13.3.2 Excluding special characters

You can just as easily decide to exclude URLs that contain your special characters as include them. Simply change the =~ (read: does match) in this line:

      $url  =~ s!($special_regex)!<font color="red">$1</font>!g and

to !~ (read: does not match), leaving:

      $url  

!

~ s!($special_regex)!<font color="red">$1</font>!g and

Now, any result containing the specific characters will not show up.