Changing your URLs: Mapping old URLs to new ones

Users wishing to change their URL structure for their blog should approach this process carefully because a change like this without planning may result in:

• readers being unable to find your content
• orphaned files on your file server whose content will be stale over time
• search engines penalizing you for having replicated content on your web site

To mitigate these risks it is often a good idea to provide your web server with a mapping file that will help redirect your readers from your old URL structure to your new one. The following document will provide you with guidance and sample code for how to complete this process.

This guide however will require customization on your part, as every user’s URL structure can be very different from one another.

Creating a URL Mapping File

This describe a process for users of the Apache web server who have the mod_rewrite plugin installed and enabled. The process involves creating an Index Template that iterates over every file in your blog and outputs a RewriteRule to map the old URL to the new URL for each file.

How it works

• The MTIfArchiveTypeEnabled tag is used to conditionally output rewrite rules for each of the allowable archive types.
• The MTArchiveList tag is responsible for iterating over each file associated with that archive type.
• The MTFileTemplate tag is used twice per file, once to output the URL format for the old structure, and again for the new structure.
• Archive File Path Specifiers are used to specify the format of each URL output by the MTFileTemplate tag.

Instructions

1. Create an Index Template called “Rewrite Rules”
2. Set the output file name to rewrite_rules.conf
3. Cut and paste and then customize the template code below into the index template
4. Publish the template
5. In your httpd.conf file or your .htaccess file, include the following text: Include /path/to/your/rewrite_rules.conf`
6. Restart Apache

When you are satisfied that everything is working, you may delete the template you created in step #1 above. But keep the rewrite_rules.conf file around forever. It will keep all of your old URLs alive forever.

Sample Template

RewriteEngine on

<MTIfArchiveTypeEnabled archive_type="Individual">
<MTArchiveList archive_type="Individual">
RewriteRule ^<mt:FileTemplate format="/%c/%i" />$ <$mt:BlogURL$><mt:FileTemplate format="%-c/%i" /> [L,R]</MTArchiveList>
</MTIfArchiveTypeEnabled>

<MTIfArchiveTypeEnabled archive_type="Monthly">
<MTArchiveList archive_type="Monthly">
RewriteRule ^<mt:FileTemplate format="/%y/%m/%i" />$ <$mt:BlogURL$><mt:FileTemplate format="%-c/%y/%m/%i" /> [L,R]</MTArchiveList>
</MTIfArchiveTypeEnabled>

<MTIfArchiveTypeEnabled archive_type="Category">
<MTTopLevelCategories>
<MTIfNonZero tag="MTCategoryCount">
RewriteRule ^<mt:FileTemplate format="/%c/%i" />$ <$mt:BlogURL$><mt:FileTemplate format="%-c/%i" /> [L,R]</MTArchiveList>
</MTIfNonZero>
</MTTopLevelCategories>
</MTIfArchiveTypeEnabled>

<MTIfArchiveTypeEnabled archive_type="Author">
<MTArchiveList archive_type="Author">
RewriteRule ^<mt:FileTemplate format="/%a/%i" />$ <$mt:BlogURL$><mt:FileTemplate format="%-a/%i" /> [L,R]</MTArchiveList>
</MTIfArchiveTypeEnabled>

<MTIfArchiveTypeEnabled archive_type="Category-Monthly">
<MTArchiveList archive_type="Category-Monthly">
RewriteRule ^<mt:FileTemplate format="/%c/%y/%m/%i" />$ <$mt:BlogURL$><mt:FileTemplate format="%-c/%y/%m/%i" /> [L,R]</MTArchiveList>
</div>
</MTIfArchiveTypeEnabled>

<MTIfArchiveTypeEnabled archive_type="Author-Monthly">
<MTArchiveList archive_type="Author-Monthly">
RewriteRule ^<mt:FileTemplate format="/%a/%y/%m/%i" />$ <$mt:BlogURL$><mt:FileTemplate format="%-a/%y/%m/%i" /> [L,R]</MTArchiveList>
</MTIfArchiveTypeEnabled>

Sample Output

RewriteRule ^/television/2008/02/index.php$ http://www.majordojo.com/television/2008/02/index.php [L,R]
RewriteRule ^/blogging/2008/02/index.php$ http://www.majordojo.com/blogging/2008/02/index.php [L,R]
RewriteRule ^/blogging/2008/01/index.php$ http://www.majordojo.com/blogging/2008/01/index.php [L,R]
RewriteRule ^/current_events/2008/01/index.php$ http://www.majordojo.com/current-events/2008/01/index.php [L,R]
RewriteRule ^/geeky_goodness/2008/01/index.php$ http://www.majordojo.com/geeky-goodness/2008/01/index.php [L,R]
RewriteRule ^/aint_it_cool/2008/01/index.php$ http://www.majordojo.com/aint-it-cool/2008/01/index.php [L,R]
RewriteRule ^/blogging/2008/01/index.php$ http://www.majordojo.com/blogging/2008/01/index.php [L,R]
RewriteRule ^/current_events/2008/01/index.php$ http://www.majordojo.com/current-events/2008/01/index.php [L,R]
RewriteRule ^/television/2008/01/index.php$ http://www.majordojo.com/television/2008/01/index.php [L,R]
RewriteRule ^/its_funny_laugh/2007/12/index.php$ http://www.majordojo.com/its-funny-laugh/2007/12/index.php [L,R]
RewriteRule ^/science_fiction/2007/12/index.php$ http://www.majordojo.com/science-fiction/2007/12/index.php [L,R]
RewriteRule ^/television/2007/12/index.php$ http://www.majordojo.com/television/2007/12/index.php [L,R]
RewriteRule ^/aint_it_cool/2007/12/index.php$ http://www.majordojo.com/aint-it-cool/2007/12/index.php [L,R]
RewriteRule ^/aint_it_cool/2007/12/index.php$ http://www.majordojo.com/aint-it-cool/2007/12/index.php [L,R]
RewriteRule ^/its_funny_laugh/2007/12/index.php$ http://www.majordojo.com/its-funny-laugh/2007/12/index.php [L,R]

Additional Resources

• Upgrade Guide
• Archive File Path Syntax
• FileTemplate Documentation
• Clean Sweep Plugin - a plugin to report 404s and keep pages alive