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Version: 2009-11-24 (ubuntu - 25/10/10)

Section: 7 (Divers)


swish.cgi -- Example Perl script for searching with the SWISH-E search engine.


"swish.cgi" is a CGI script for searching with the SWISH-E search engine version 2.1-dev and above. It returns results a page at a time, with matching words from the source document highlighted, showing a few words of content on either side of the highlighted word.

The script is highly configurable. Features include searching multiple (or selectable) indexes, limiting searches to a subset of documents, sorting by a number of different properties, and limiting results to a date range.

On unix type systems the swish.cgi script is installed in the directory $prefix/lib/swish-e, which is typically /usr/local/lib/swish-e. This can be overridden by the configure options --prefix or --libexecdir.

The standard configuration (i.e. not using a config file) should work with most swish index files. Customization of the parameters will be needed if you are indexing special meta data and want to search and/or display the meta data. The configuration can be modified by editing this script directly, or by using a configuration file (.swishcgi.conf by default). The script's configuration file is described below.

You are strongly encouraged to get the default configuration working before making changes. Most problems using this script are the result of configuration modifications.

The script is modular in design. Both the highlighting code and output generation is handled by modules, which are included in the example/modules distribution directory and installed in the $libexecdir/perl directory. This allows for easy customization of the output without changing the main CGI script.

Included with the Swish-e distribution is a module to generate standard HTML output. There's also modules and template examples to use with the popular Perl templating systems HTML::Template and Template-Toolkit. This is very useful if your site already uses one of these templating systems The HTML::Template and Template-Toolkit packages are not distributed with Swish-e. They are available from the CPAN (http://search.cpan.org).

This scipt can also run basically unmodified as a mod_perl handler, providing much better performance than running as a CGI script. Usage under mod_perl is described below.

Please read the rest of the documentation. There's a "DEBUGGING" section, and a "FAQ" section.

This script should work on Windows, but security may be an issue.


A reasonably current version of Perl. 5.00503 or above is recommended (anything older will not be supported).

The Date::Calc module is required to use the date range feature of the script. The Date::Calc module is also available from CPAN.


Here's an example installation session under Linux. It should be similar for other operating systems.

For the sake of simplicity in this installation example all files are placed in web server space, including files such as swish-e index and configuration files that would normally not be made available via the web server. Access to these files should be limited once the script is running. Either move the files to other locations (and adjust the script's configuration) or use features of the web server to limit access (such as with .htaccess).

Please get a simple installation working before modifying the configuration file. Most problems reported for using this script have been due to improper configuration.

The script's default settings are setup for initial testing. By default the settings expect to find most files and the swish-e binary in the same directory as the script.

For security reasons, once you have tested the script you will want to change settings to limit access to some of these files by the web server (either by moving them out of web space, or using access control such as .htaccess). An example of using .htaccess on Apache is given below.

It's expected that swish-e has already been unpacked and the swish-e binary has be compiled from source and ``make install'' has been run. If swish-e was installed from a vendor package (such as from a RPM or Debian package) see that pakage's documentation for where files are installed.

Example Installation:

1 Symlink or copy the swish.cgi.
Symlink (or copy if your platform or webserver does not allow symlinks) the swish.cgi script from the installation directory to a local directory. Typically, this would be the cgi-bin directory or a location where CGI script are located. In this example a new directory is created and the script is symlinked.
     ~$ mkdir swishdir
     ~$ cd swishdir
     ~/swishdir$ ln -s /usr/local/lib/swish-e/swish.cgi

The installation directory is set at configure time with the --prefix or --libexecdir options, but by default is in /usr/local/lib/swish-e.

2 Create an index
Use an editor and create a simple configuration file for indexing your files. In this example the Apache documentation is indexed. Last we run a simple query to test that the index works correctly.
     ~/swishdir$ cat swish.conf
     IndexDir /usr/local/apache/htdocs
     IndexOnly .html .htm
     DefaultContents HTML*
     StoreDescription HTML* <body> 200000
     MetaNames swishdocpath swishtitle
     ReplaceRules remove /usr/local/apache/

If you do not have the Apache docs installed then pick another directory to index such as /usr/share/doc.

Create the index.

     ~/swishdir$ swish-e -c swish.conf
     Indexing Data Source: "File-System"
     Indexing "/usr/local/apache/htdocs"
     Removing very common words...
     no words removed.
     Writing main index...
     Sorting words ...
     Sorting 7005 words alphabetically
     Writing header ...
     Writing index entries ...
       Writing word text: Complete
       Writing word hash: Complete
       Writing word data: Complete
     7005 unique words indexed.
     5 properties sorted.
     124 files indexed.  1485844 total bytes.  171704 total words.
     Elapsed time: 00:00:02 CPU time: 00:00:02
     Indexing done!

Now, verify that the index can be searched:

     ~/swishdir$ swish-e -w install -m 1
     # SWISH format: 2.1-dev-25
     # Search words: install
     # Number of hits: 14
     # Search time: 0.001 seconds
     # Run time: 0.040 seconds
     1000 htdocs/manual/dso.html "Apache 1.3 Dynamic Shared Object (DSO) support" 17341

Let's see what files we have in our directory now:

     ~/swishdir$ ls -1
3 Test the CGI script
This is a simple step, but often overlooked. You should test from the command line instead of jumping ahead and testing with the web server. See the "DEBUGGING" section below for more information.
     ~/swishdir$ ./swish.cgi | head
     Content-Type: text/html; charset=ISO-8859-1
     <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
               Search our site

The above shows that the script can be run directly, and generates a correct HTTP header and HTML.

If you run the above and see something like this:

     ~/swishdir >./swish.cgi
     bash: ./swish.cgi: No such file or directory

then you probably need to edit the script to point to the correct location of your perl program. Here's one way to find out where perl is located (again, on unix):

     ~/swishdir$ which perl
     ~/swishdir$ /usr/local/bin/perl -v
     This is perl, v5.6.0 built for i586-linux

Good! We are using a reasonably current version of perl.

Now that we know perl is at /usr/local/bin/perl we can adjust the ``shebang'' line in the perl script (e.g. the first line of the script):

     ~/swishdir$ pico swish.cgi
     (edit the #! line)
     ~/swishdir$ head -1 swish.cgi
     #!/usr/local/bin/perl -w
4 Test with the web server
How you do this is completely dependent on your web server, and you may need to talk to your web server admin to get this working. Often files with the .cgi extension are automatically set up to run as CGI scripts, but not always. In other words, this step is really up to you to figure out!

This example shows creating a symlink from the web server space to the directory used above. This will only work if the web server is configured to follow symbolic links (the default for Apache).

This operation requires root access:

     ~/swishdir$ su -c "ln -s $HOME/swishdir /usr/local/apache/htdocs/swishdir"
     Password: *********

If your account is on an ISP and your web directory is ~/public_html the you might just move the entire directory:

     mv ~/swishdir ~/public_html

Now, let's make a real HTTP request:

     ~/swishdir$ GET http://localhost/swishdir/swish.cgi | head -3
     #!/usr/local/bin/perl -w
     package SwishSearch;
     use strict;

Oh, darn. It looks like Apache is not running the script and instead returning it as a static page. Apache needs to be told that swish.cgi is a CGI script.

.htaccess comes to the rescue:

     ~/swishdir$ cat .htaccess
     # Deny everything by default
     Deny From All
     # But allow just CGI script
     <files swish.cgi>
         Options ExecCGI
         Allow From All
         SetHandler cgi-script

That ``Deny From All'' prevents access to all files (such as config and index files), and only access is allowed to the swish.cgi script.

Let's try the request one more time:

     ~/swishdir >GET http://localhost/swishdir/swish.cgi | head
     <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
               Search our site
             <a href="http://swish-e.org">

That looks better! Now use your web browser to test.

Now, you may note that the links are not valid on the search results page. The swish config file contained the line:

      ReplaceRules remove /usr/local/apache/

To make those links works (and assuming your web server will follow symbolic links):

     ~/swishtest$ ln -s /usr/local/apache/htdocs

BTW - ``GET'' used above is a program included with Perl's LWP library. If you do no have this you might try something like:

     wget -O - http://localhost/swishdir/swish.cgi | head

and if nothing else, you can always telnet to the web server and make a basic request.

     ~/swishtest$ telnet localhost 80
     Connected to localhost.
     Escape character is '^]'.
     GET /swishtest/swish.cgi http/1.0
     HTTP/1.1 200 OK
     Date: Wed, 13 Feb 2002 20:14:31 GMT
     Server: Apache/1.3.20 (Unix) mod_perl/1.25_01
     Connection: close
     Content-Type: text/html; charset=ISO-8859-1
     <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
               Search our site

This may seem like a lot of work compared to using a browser, but browsers are a poor tool for basic CGI debugging.

If you have problems check the "DEBUGGING" section below.


If you want to change the location of the swish-e binary or the index file, use multiple indexes, add additional metanames and properties, change the default highlighting behavior, etc., you will need to adjust the script's configuration settings.

Again, please get a test setup working with the default parameters before making changes to any configuration settings. Better to debug one thing at a time...

In general, you will need to adjust the script's settings to match the index file you are searching. For example, if you are indexing a hypermail list archive you may want to make the script use metanames/properties of Subject, Author, and, Email address. Or you may wish to provide a way to limit searches to subsets of documents (e.g. parts of your directory tree).

To make things somewhat ``simple'', the configuration parameters are included near the top of the swish.cgi program. That is the only place that the individual parameters are defined and explained, so you will need to open up the swish.cgi script in an editor to view the options. Further questions about individual settings should be referred to the swish-e discussion list.

The parameters are all part of a perl "hash" structure, and the comments at the top of the program should get you going. The perl hash structure may seem a bit confusing, but it makes it easy to create nested and complex parameters. Syntax is important, so cut-n-paste should be your best defense if you are not a perl programmer.

By the way, Perl has a number of quote operators. For example, to quote a string you might write:

     title => 'Search My Site',

Some options take more than one parameter, where each parameter must be quoted. For example:

     metanames => [ 'swishdefault', 'swishtitle',  'swishdocpath' ],

which assigns an array ( [...] ) of three strings to the ``metanames'' variable. Lists of quoted strings are so common in perl that there's a special operator called ``qw'' (quote word) to save typing all those quotes:

     metanames => [ qw/ swishdefault swishtitle swishdocpath / ],

or to use the parenthesis as the quote character (you can pick any):

     metanames => [ qw( swishdefault swishtitle swishdocpath ) ],

There are two options for changing the configuration settings from their default values: One way is to edit the script directly, or the other was is to use a separate configuration file. In either case, the configuration settings are a basic perl hash reference.

Using a configuration file is described below, but contains the same hash structure.

There are many configuration settings, and some of them are commented out either by using a ``#'' symbol, or by simply renaming the configuration directive (e.g. by adding an ``x'' to the parameter name).

A very basic configuration setup might look like:

     return {
         title           => 'Search the Swish-e list',   # Title of your choice.
         swish_binary    => 'swish-e',                   # Location of swish-e binary
         swish_index     => 'index.swish-e',             # Location of your index file

Or if searching more than one index:

     return {
         title           => 'Search the Swish-e list',
         swish_binary    => 'swish-e',
         swish_index     => ['index.swish-e', 'index2'],

Both of these examples return a reference to a perl hash ( "return {...}" ). In the second example, the multiple index files are set as an array reference.

Note that in the example above the swish-e binary file is relative to the current directory. If running under mod_perl you will need to use absolute paths.

The script can also use the SWISH::API perl module (included with the swish-e distribution in the perl directory) to access the swish-e index. The "use_library" option is used to enable the use of the SWISH::API module:

     return {
         title           => 'Search the Swish-e list',
         swish_index     => ['index.swish-e', 'index2'],
         use_library     => 1, # enable use of the SWISH::API module

The module must be available via the @INC array, like all Perl modules.

Using the SWISH::API module avoids the need to fork and execute a the swish-e program. Under mod_perl you will may see a significant performance improvement when using the SWISH::API module. Under normal CGI usage you will probably not see any speed improvements.

Using A Configuration File

As mentioned above, configuration settings can be either set in the swish.cgi script, or set in a separate configuration file. Settings in a configuration file will override the settings in the script.

By default, the swish.cgi script will attempt to read settings from the file .swishcgi.conf. For example, you might only wish to change the title used in the script. Simply create a file called .swishcgi.conf in the same directory as the CGI script:

     > cat .swishcgi.conf
     # Example swish.cgi configuration script.
     return {
        title => 'Search Our Mailing List Archive',

The settings you use will depend on the index you create with swish:

    return {
         title           => 'Search the Apache documentation',
         swish_binary    => 'swish-e',
         swish_index     => 'index.swish-e',
         metanames       => [qw/swishdefault swishdocpath swishtitle/],
         display_props   => [qw/swishtitle swishlastmodified swishdocsize swishdocpath/],
         title_property  => 'swishdocpath',
         prepend_path    => 'http://myhost/apachedocs',
         name_labels => {
             swishdefault        => 'Search All',
             swishtitle          => 'Title',
             swishrank           => 'Rank',
             swishlastmodified   => 'Last Modified Date',
             swishdocpath        => 'Document Path',
             swishdocsize        => 'Document Size',

The above configuration defines metanames to use on the form. Searches can be limited to these metanames.

``display_props'' tells the script to display the property ``swishlastmodified'' (the last modified date of the file), the document size, and path with the search results.

The parameter ``name_labels'' is a hash (reference) that is used to give friendly names to the metanames.

Here's another example. Say you want to search either (or both) the Apache 1.3 documentation and the Apache 2.0 documentation indexed seperately.

     return {
        title       => 'Search the Apache Documentation',
        date_ranges => 0,
        swish_index => [ qw/ index.apache index.apache2 / ],
        select_indexes  => {
             method  => 'checkbox_group',
             labels  => [ '1.3.23 docs', '2.0 docs' ],  # Must match up one-to-one to swish_index
             description => 'Select: ',

Now you can select either or both sets of documentation while searching.

All the possible settings are included in the default configuration located near the top of the swish.cgi script. Open the swish.cgi script with an editor to look at the various settings. Contact the Swish-e Discussion list for help in configuring the script.


Most problems with using this script have been a result of improper configuration. Please get the script working with default settings before adjusting the configuration settings.

The key to debugging CGI scripts is to run them from the command line, not with a browser.

First, make sure the program compiles correctly:

     $ perl -c swish.cgi
     swish.cgi syntax OK

Next, simply try running the program:

     $ ./swish.cgi | head
     Content-Type: text/html; charset=ISO-8859-1
     <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
               Search our site

Under Windows you will need to run the script as:

    C:\wwwroot\swishtest> perl swish.cgi

Now, you know that the program compiles and will run from the command line. Next, try accessing the script from a web browser.

If you see the contents of the CGI script instead of its output then your web server is not configured to run the script. With Apache look at settings like ScriptAlias, SetHandler, and Options.

If an error is reported (such as Internal Server Error or Forbidden) you need to locate your web server's error_log file and carefully read what the problem is. Contact your web administrator for help locating the web server's error log.

If you don't have access to the web server's error_log file, you can modify the script to report errors to the browser screen. Open the script and search for ``CGI::Carp''. (Author's suggestion is to debug from the command line --- adding the browser and web server into the equation only complicates debugging.)

The script does offer some basic debugging options that allow debugging from the command line. The debugging options are enabled by setting an environment variable ``SWISH_DEBUG''. How that is set depends on your operating system and the shell you are using. These examples are using the ``bash'' shell syntax.

Note: You can also use the ``debug_options'' configuration setting, but the recommended method is to set the environment variable.

You can list the available debugging options like this:

     $ SWISH_DEBUG=help ./swish.cgi >outfile
     Unknown debug option 'help'.  Must be one of:
            basic: Basic debugging
          command: Show command used to run swish
          headers: Show headers returned from swish
           output: Show output from swish
          summary: Show summary of results
             dump: Show all data available to templates

Debugging options may be combined:

     $ SWISH_DEBUG=command,headers,summary ./swish.cgi >outfile

You will be asked for an input query and the max number of results to return. You can use the defaults in most cases. It's a good idea to redirect output to a file. Any error messages are sent to stderr, so those will still be displayed (unless you redirect stderr, too).

Here are some examples:

     ~/swishtest$ SWISH_DEBUG=basic ./swish.cgi >outfile
     Debug level set to: 1
     Enter a query [all]:
     Using 'not asdfghjklzxcv' to match all records
     Enter max results to display [1]:
     ------ Can't use DateRanges feature ------------
     Script will run, but you can't use the date range feature
     Can't locate Date/Calc.pm in @INC (@INC contains: modules /usr/local/lib/perl5/5.6.0/i586-linux /usr/local/lib/perl5/5.6.0 /usr/local/lib/perl5/site_perl/5.6.0/i586-linux /usr/local/lib/perl5/site_perl/5.6.0 /usr/local/lib/perl5/site_perl/5.005/i586-linux /usr/local/lib/perl5/site_perl/5.005 /usr/local/lib/perl5/site_perl .) at modules/DateRanges.pm line 107, <STDIN> line 2.
     BEGIN failed--compilation aborted at modules/DateRanges.pm line 107, <STDIN> line 2.
     Compilation failed in require at ./swish.cgi line 971, <STDIN> line 2.
     Can't exec "./swish-e": No such file or directory at ./swish.cgi line 1245, <STDIN> line 2.
     Child process Failed to exec './swish-e' Error: No such file or directory at ./swish.cgi line 1246, <STDIN> line 2.
     Failed to find any results

The above indicates two problems. First problem is that the Date::Calc module is not installed. The Date::Calc module is needed to use the date limiting feature of the script.

The second problem is a bit more serious. It's saying that the script can't find the swish-e binary file. In this example it's specified as being in the current directory. Either correct the path to the swish-e binary, or make a local copy or symlink to the swish-e binary.

     ~/swishtest$ cat .swishcgi.conf
         return {
            title       => 'Search the Apache Documentation',
            swish_binary => '/usr/local/bin/swish-e',
            date_ranges => 0,

Now, let's try again:

     ~/swishtest$ SWISH_DEBUG=basic ./swish.cgi >outfile
     Debug level set to: 1
     ---------- Read config parameters from '.swishcgi.conf' ------
     $VAR1 = {
               'date_ranges' => 0,
               'title' => 'Search the Apache Documentation'
     Enter a query [all]:
     Using 'not asdfghjklzxcv' to match all records
     Enter max results to display [1]:
     Found 1 results
     Can't locate SWISH::TemplateDefault.pm in @INC (@INC contains: modules /usr/local/lib/perl5/5.6.0/i586-linux /usr/local/lib/perl5/5.6.0 /usr/local/lib/perl5/site_perl/5.6.0/i586-linux /usr/local/lib/perl5/site_perl/5.6.0 /usr/local/lib/perl5/site_perl/5.005/i586-linux /usr/local/lib/perl5/site_perl/5.005 /usr/local/lib/perl5/site_perl .) at ./swish.cgi line 608.

This means that the swish.cgi script could not locate a required module. To correct this locate where the SWISH::Template module is installed and add a ``use lib'' line to your configuration file (or to the swish.cgi script):

     ~/swishtest$ cat .swishcgi.conf
     use lib '/home/bill/local/lib/perl';
     return {
        title       => 'Search the Apache Documentation',
        date_ranges => 0,
     ~/swishtest$ SWISH_DEBUG=basic ./swish.cgi >outfile
     Debug level set to: 1
     ---------- Read config parameters from '.swishcgi.conf' ------
     $VAR1 = {
               'date_ranges' => 0,
               'title' => 'Search the Apache Documentation'
     Enter a query [all]:
     Using 'not asdfghjklzxcv' to match all records
     Enter max results to display [1]:
     Found 1 results

That is much better!

The ``use lib'' statement tells Perl where to look for modules by adding the path supplied to an array called @INC.

Note that most modules are in the SWISH namespace. For example, the default output module is called SWISH::TemplateDefault. When Perl is looking for that module it is looking for the file SWISH/TemplateDefault.pm. If the ``use lib'' statement is set as:

     use lib '/home/bill/local/lib/perl';

then Perl will look (among other places) for the file


when attempting to load the SWISH::TemplateDefault module. Relative paths may also be used.

     use lib 'modules';

will cause Perl to look for the file:


relative to where the swish.cgi script is running. (This is not true when running under mod_perl).

Here's another common problem. Everything checks out, but when you run the script you see the message:

     Swish returned unknown output

Ok, let's find out what output it is returning:

     ~/swishtest$ SWISH_DEBUG=headers,output ./swish.cgi >outfile
     Debug level set to: 13
     ---------- Read config parameters from '.swishcgi.conf' ------
     $VAR1 = {
               'swish_binary' => '/usr/local/bin/swish-e',
               'date_ranges' => 0,
               'title' => 'Search the Apache Documentation'
     Enter a query [all]:
     Using 'not asdfghjklzxcv' to match all records
     Enter max results to display [1]:
       usage: swish [-i dir file ... ] [-S system] [-c file] [-f file] [-l] [-v (num)]
     version: 2.0
        docs: http://sunsite.berkeley.edu/SWISH-E/
     *** 9872 Failed to run swish: 'Swish returned unknown output' ***
     Failed to find any results

Oh, looks like /usr/local/bin/swish-e is version 2.0 of swish. We need 2.1-dev and above!

Frequently Asked Questions

Here's some common questions and answers.

How do I change the way the output looks?

The script uses a module to generate output. By default it uses the SWISH::TemplateDefault.pm module. The module used is selected in the swish.cgi configuration file. Modules are located in the example/modules/SWISH directory in the distribution, but are installed in the $prefix/lib/swish-e/perl/SWISH/ directory.

To make simple changes you can edit the installed SWISH::TemplatDefault module directly, otherwise make a copy of the module and modify its package name. For example, change directories to the location of the installed module and copy the module to a new name:

     $ cp TemplateDefault.pm MyTemplateDefault.pm

Then at the top of the module adjust the ``package'' line to:

     package SWISH::MyTemplateDefault;

To use this modules you need to adjust the configuration settings (either at the top of swish.cgi or in a configuration file:

         template => {
             package     => 'SWISH::MyTemplateDefault',

The module does not need to be in the SWISH namespace, and can be stored in any location as long as the module can be found via the @INC array (i.e. modify the ``use lib'' statement in swish.cgi if needed).

How do I use a templating system with swish.cgi?

In addition to the TemplateDefault.pm module, the swish-e distribution includes two other Perl modules for generating output using the templating systems HTML::Template and Template-Toolkit.

Templating systems use template files to generate the HTML, and make maintaining the look of a large (or small) site much easier. HTML::Template and Template-Toolkit are separate packages and can be downloaded from the CPAN. See http://search.cpan.org.

Two basic templates are provided as examples for generating output using these templating systems. The example templates are located in the example directory. The module SWISH::TemplateHTMLTemplate uses the file swish.tmpl to generate its output, while the module SWISH::TemplateToolkit uses the swish.tt file. (Note: swish.tt was renamed from search.tt Jun 03, 2004.)

To use either of these modules you will need to adjust the ``template'' configuration setting. Examples for both templating systems are provided in the configuration settings near the top of the swish.cgi program.

Use of these modules is an advanced usage of swish.cgi and are provided as examples only.

All of the output generation modules are passed a hash with the results from the search, plus other data use to create the output page. You can see this hash by using the debugging option ``dump'' or by using the included SWISH::TemplateDumper module:

     ~/swishtest >cat .swishcgi.conf
         return {
            title       => 'Search the Apache Documentation',
            template => {
                 package     => 'SWISH::TemplateDumper',

And run a query. For example:


Why are there three different highlighting modules?

Three are three highlighting modules included with the swish-e distribution. Each is a trade-off of speed vs. accuracy:
     SWISH::DefaultHighlight - reasonably fast, but does not highlight phrases
     SWISH::PhraseHighlight  - reasonably slow, but is reasonably accurate
     SWISH::SimpleHighlight  - fast, some phrases, but least accurate

Eh, the default is actually ``PhraseHighlight''. Oh well.

All of the highlighting modules slow down the script. Optimizations to these modules are welcome!

My ISP doesn't provide access to the web server logs

There are a number of options. One way it to use the CGI::Carp module. Search in the swish.cgi script for:
     use Carp;
     # Or use this instead -- PLEASE see perldoc CGI::Carp for details
     # use CGI::Carp qw(fatalsToBrowser warningsToBrowser);

And change it to look like:

     #use Carp;
     # Or use this instead -- PLEASE see perldoc CGI::Carp for details
     use CGI::Carp qw(fatalsToBrowser warningsToBrowser);

This should be only for debugging purposes, as if used in production you may end up sending quite ugly and confusing messages to your browsers.

Why does the output show (NULL)?

Swish-e displays (NULL) when attempting to display a property that does not exist in the index.

The most common reason for this message is that you did not use StoreDescription in your config file while indexing.

     StoreDescription HTML* <body> 200000

That tells swish to store the first 200,000 characters of text extracted from the body of each document parsed by the HTML parser. The text is stored as property ``swishdescription''.

The index must be recreated after changing the swish-e configuration.


     ~/swishtest > ./swish-e -T index_metanames

will display the properties defined in your index file.

This can happen with other properties, too. For example, this will happen when you are asking for a property to display that is not defined in swish.

     ~/swishtest > ./swish-e -w install -m 1 -p foo
     # SWISH format: 2.1-dev-25
     # Search words: install
     err: Unknown Display property name "foo"
     ~/swishtest > ./swish-e -w install -m 1 -x 'Property foo=<foo>\n'
     # SWISH format: 2.1-dev-25
     # Search words: install
     # Number of hits: 14
     # Search time: 0.000 seconds
     # Run time: 0.038 seconds
     Property foo=(NULL)

To check that a property exists in your index you can run:

     ~/swishtest > ./swish-e -w not dkdk -T index_metanames | grep foo
             foo : id=10 type=70  META_PROP:STRING(case:ignore) *presorted*

Ok, in this case we see that ``foo'' is really defined as a property. Now let's make sure swish.cgi is asking for ``foo'' (sorry for the long lines):

     ~/swishtest > SWISH_DEBUG=command ./swish.cgi > /dev/null
     Debug level set to: 3
     Enter a query [all]:
     Using 'not asdfghjklzxcv' to match all records
     Enter max results to display [1]:
     ---- Running swish with the following command and parameters ----
     ./swish-e  \
     -w  \
     'swishdefault=(not asdfghjklzxcv)'  \
     -b  \
     1  \
     -m  \
     1  \
     -f  \
     index.swish-e  \
     -s  \
     swishrank  \
     desc  \
     swishlastmodified  \
     desc  \
     -x  \
     '<swishreccount>\t<swishtitle>\t<swishdescription>\t<swishlastmodified>\t<swishdocsize>\t<swishdocpath>\t<fos>\t<swishrank>\t<swishdocpath>\n'  \
     -H  \

If you look carefully you will see that the -x parameter has ``fos'' instead of ``foo'', so there's our problem.

How do I use the SWISH::API perl module with swish.cgi?

Use the "use_library" configuration directive:
     use_library => 1,

This will only provide improved performance when running under mod_perl or other persistent environments.

Why does the Run time differ when using the SWISH::API module

When using the SWISH::API module the run (and search) times are calculated within the script. When using the swish-e binary the swish-e program reports the times. The ``Run time'' may include the time required to load and compile the SWISH::API module.


This script can be run under mod_perl (see http://perl.apache.org). This will improve the response time of the script compared to running under CGI by loading the swish.cgi script into the Apache web server.

You must have a mod_perl enabled Apache server to run this script under mod_perl.

Configuration is simple. In your httpd.conf or your startup.pl file you need to load the script. For example, in httpd.conf you can use a perl section:

         use lib '/usr/local/apache/cgi-bin';  # location of the swish.cgi file
         use lib '/home/yourname/swish-e/example/modules';  # modules required by swish.cgi
         require "swish.cgi";

Again, note that the paths used will depend on where you installed the script and the modules. When running under mod_perl the swish.cgi script becomes a perl module, and therefore the script does not need to be installed in the cgi-bin directory. (But, you can actually use the same script as both a CGI script and a mod_perl module at the same time, read from the same location.)

The above loads the script into mod_perl. Then to configure the script to run add this to your httpd.conf configuration file:

     <location /search>
         PerlSetVar Swish_Conf_File /home/yourname/swish-e/myconfig.pl
         allow from all
         SetHandler perl-script
         PerlHandler SwishSearch

Note that you use the ``Swish_Conf_File'' setting in httpd.conf to tell the script which config file to use. This means you can use the same script (and loaded modules) for different search sites (running on the same Apache server). You can just specify differnt config files for each Location and they can search different indexes and have a completely different look for each site, but all share the same code.

Note that the config files are cached in the swish.cgi script. Changes to the config file will require restarting the Apache server before they will be reloaded into the swish.cgi script. This avoids calling stat() for every request.

Unlike CGI, mod_perl does not change the current directory to the location of the script, so your settings for the swish binary and the path to your index files must be absolute paths (or relative to the server root).

Using the SWISH::API module with mod_perl will provide the most performance improvements. Use of the SWISH::API module can be enabled by the configuration setting "use_library":

     use_library     => 1,

Without highlighting code enabled, using the SWISH::API module resulted in about 20 requests per second, where running the swish-e binary slowed the script down to about 8 requests per second.

Note that the highlighting code is slow. For the best search performance turn off highlighting. In your config file you can add:

     highlighting    => 0,  # disable highlighting

and the script will show the first 500 chars of the description (or whatever you set for ``max_chars''). Without highlight one test was processing about 20 request per second. With The ``PhraseHighlight'' module that dropped to a little better than two requests per second, ``DefaultHighlight'' was about 2.3 request per second, and ``SimpleHighlight'' was about 6 request per second.

Experiement with different highlighting options when testing performance.

Please post to the swish-e discussion list if you have any questions about running this script under mod_perl.

Here's some general request/second on an Athlon XP 1800+ with 1/2GB RAM, Linux 2.4.20.

                               Highlighting Mode
                       None     Phrase    Default     Simple
    Using SWISH::API   45        1.5        2          12
    Using swish-e      12        1.3       1.8         7.5

As you can see the highlighting code is a limiting factor.


SpeedyCGI (also called PersistentPerl) is another way to run Perl scripts persistently. SpeedyCGI is good if you do not have mod_perl available or do not have root access. SpeedyCGI works on Unix systems by loading the script into a ``back end'' process and keeping it in memory between requests. New requests are passed to the back end processes which avoids the startup time required by a Perl CGI script.

Install SpeedyCGI from http://daemoninc.com/ (your OS may provide a packaged version of SpeedyCGI) and then change the first line of swish.cgi. For example, if the speedy binary is installed in /usr/bin/speedy, use the line:

     #! /usr/bin/speedy -w -- -t60

The -w option is passed to Perl, and all options following the double-dash are SpeedyCGI options.

Note that when using SpeedyCGI configuration data is cached in memory. If you change the swish.cgi configuration file (.swishcgi.conf) then touch the main swish.cgi script to force reloading of configuration data.


There are two ways to spider with swish-e. One uses the ``http'' input method that uses code that's part of swish. The other way is to use the new ``prog'' method along with a perl helper program called "spider.pl".

Here's an example of a configuration file for spidering with the ``http'' input method. You can see that the configuration is not much different than the file system input method. (But, don't use the http input method --- use the -S prog method shown below.)

     # Define what to index
     IndexDir http://www.myserver.name/index.html
     IndexOnly .html .htm
     IndexContents HTML* .html .htm
     DefaultContents HTML*
     StoreDescription HTML* <body> 200000
     MetaNames swishdocpath swishtitle
     # Define http method specific settings -- see swish-e documentation
     SpiderDirectory ../swish-e/src/
     Delay 0

You index with the command:

     swish-e -S http -c spider.conf

Note that this does take longer. For example, spidering the Apache documentation on a local web server with this method took over a minute, where indexing with the file system took less than two seconds. Using the ``prog'' method can speed this up.

Here's an example configuration file for using the ``prog'' input method:

     # Define the location of the spider helper program
     IndexDir ../swish-e/prog-bin/spider.pl
     # Tell the spider what to index.
     SwishProgParameters default http://www.myserver.name/index.html
     IndexContents HTML* .html .htm
     DefaultContents HTML*
     StoreDescription HTML* <body> 200000
     MetaNames swishdocpath swishtitle

Then to index you use the command:

     swish-e -c prog.conf -S prog -v 0

Spidering with this method took nine seconds.

Stemmed Indexes

Many people enable a feature of swish called word stemming to provide ``fuzzy'' search options to their users. The stemming code does not actually find the ``stem'' of word, rather removes and/or replaces common endings on words. Stemming is far from perfect, and many words do not stem as you might expect. Plus, currently only English is supported. But, it can be a helpful tool for searching your site. You may wish to create both a stemmed and non-stemmed index, and provide a checkbox for selecting the index file.

To enable a stemmed index you simply add to your configuration file:

     UseStemming yes

If you want to use a stemmed index with this program and continue to highlight search terms you will need to install a perl module that will stem words. This section explains how to do this.

The perl module is included with the swish-e distribution. It can be found in the examples directory (where you found this file) and called something like:


The module should also be available on CPAN (http://search.cpan.org/).

Here's an example session for installing the module. (There will be quite a bit of output when running make.)

     % gzip -dc SWISH-Stemmer-0.05.tar.gz |tar xof -
     % cd SWISH-Stemmer-0.05
     % perl Makefile.PL
     % perl Makefile.PL PREFIX=$HOME/perl_lib
     % make
     % make test
     (perhaps su root at this point if you did not use a PREFIX)
     % make install
     % cd ..

Use the PREFIX if you do not have root access or you want to install the modules in a local library. If you do use a PREFIX setting, add a "use lib" statement to the top of this swish.cgi program.

For example:

     use lib qw(

Once the stemmer module is installed, and you are using a stemmed index, the "swish.cgi" script will automatically detect this and use the stemmer module.


Please use this CGI script at your own risk.

This script has been tested and used without problem, but you should still be aware that any code running on your server represents a risk. If you have any concerns please carefully review the code.

See http://www.w3.org/Security/Faq/www-security-faq.html

Security on Windows questionable.


The SWISH-E discussion list is the place to ask for any help regarding SWISH-E or this example script. See http://swish-e.org.

Before posting please review:


Please do not contact the author or any of the swish-e developers directly.


swish.cgi $Revision: 1830 $ Copyright (C) 2001 Bill Moseley search@hank.org Example CGI program for searching with SWISH-E

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.


Bill Moseley