The problem doesnt seem to be exactly new, but apparently not as common as one might think either: You want to migrate your  MediaWiki wiki pages into a (existing) Trac installation.

The following is the indirect path to the solution with explanations on how things work. for the direct solution go to section Direct Solution.

Indirect Solution

The  TracHelpPage says regarding this issue:

You can use the  attachment:wiki:TracWiki:mediawiki2trac.py Download script as a starting point. WikiProcessor for the MediaWiki styles has been started as trac plugin on  http://trac-hacks.org/wiki/MediaWikiPluginMacro.

You are supposed to download the mentioned mediawiki2trac.py from the above link, copy it into a directory on your (web)server and execute it with e.g.:

    python /PATH/mw2tw.py > mwexport-mediawiki2trac.sql

Unfortunately the script does only some minor importing without regard to versions, attachments (i.e. associated files) and redirects etc.

A bit more interesting is the following Trac ticket:  http://trac.edgewall.org/ticket/5241 especially regarding the different handling of attachment/media-files in MediaWiki and TracWiki. MediaWiki handles attached files in a completely different way than Trac does:

In Trac, you have attached files that are associated with a given page. Whereas in MediaWiki you have files that are uploaded and it's up to the wiki-editors to create links to the uploaded documents.
So, the process for dealing with "attachments" depends on a couple of factors.
If you want your downloaded documents to be unique in Trac like they are in mediawiki, then that's a problem. AFAIK, uniqueness in mediawiki is based on the filename whereas in Trac it's a combination of filename and what Wiki page the attachment is associated with.
So if you have an attachment that is linked in multiple places from on your MediaWiki page, then to have the same effect you'd either have to set up an independent web for these attachments (so all things would link to the same file) or you need to give up on the notion that the file is unique and that you have attachments that represent copies of the file in question.

So - whats wrong here:

• First we don't want redirect pages to create stub-pages in Trac with no redirect functionality.
• Secondly existing media-references should be kept intact.

As I am not really proficient with Python I reimplemented the migration script with PHP:

Features

• Import directly from the MediaWiki MySql database into the Trac Sqlite3 database file
• Convert basic MediaWiki markup to Trac markup (so no  separate MediaWiki parser for trac is needed)
• Optionally remove category entries from wiki pages
• Preserving Image/Media links. This assumes you manually copy the old mediawiki attachment files into a new flattened out directory (without the hashed subdirectories)
• Optionally migrate revision comments
• Optionally keep redirect-links intact. Even though Trac doesn't know redirects as MediaWiki does the script will change links to redirect pages so the link directly points to the real page
• Optionally discard Stub pages
• Optionally discard pages with fewer than X bytes
• Remove custom specified substrings from pages (e.g. old MediaWiki templates)
• Replace custom specified substrings with replacement-strings (e.g. custom copyright notices)

Limitations

There are some limitations though:

• Complex markup (e.g. tables) will not be converted
• As the script directly accesses the Trac Sqlite3 database file the corresponding Sqlite3 extension needs to be enabled in PHP
• I personally didnt need this feature, so the script discards old revisions - if you take a look at the old python version of this script it shouldnt be hard to implement this though

Direct Solution

1. Backup your trac database file - seriously - do it!
2. Download and unzip the following script into a web-accessible directory on your webserver:  mediawiki2trac.zip
3. Edit the settings section at the start of the script - comments should hopefully be self-explanatory.
4. Call mediawiki2trac.php in a web browser.
   1. You need Sqlite3 support in PHP for the script to work. If you get an error message like Fatal error: Class 'SQLite3' not found in.... you are missing the extension. See for example  http://ubuntuforums.org/showthread.php?t=891767 on how to install this on Ubuntu.
   2. When calling the script it first starts in test-mode showing you what replacements etc would be done. Activate live processing by clicking on the given link.

No idea why, but I couldn't get custom files in Trac's /htdocs/ folder to be accessible using e.g.

<Location "/robots.txt">
    SetHandler None
</Location>

This caused some headaches on how to make this Trac installation / Blog accessible to Google. In the end three plugins helped to

1. make Google see my robots.txt:  RobotsTxtPlugin
2. verify the site in Google Webmaster Central:  GoogleWebmasterVerifyPlugin
3. enable Google Analytics:  TracGoogleAnalytics

The usual

    sudo easy_install svn-path-to-the-plugin

and restarting apache was all to get those 3 working.

On Ubuntu:

The BASEDIR environment variable is not defined correctly. This environment variable is needed to run this program

Dont fall into the same trap as me and remember to give executive permissions to the .sh and .jar files in TeamCity/bin after uploading the new  TeamCity files from Windows.

By the way - to include a build-status of your Teamcity installation in trac create a file TeamCityPlugin.py in your trac/plugins folder:

from trac.wiki.macros import WikiMacroBase
import urllib

class TeamCityStatusMacro(WikiMacroBase):
    """Inserts the current build status into the wiki page."""

    def expand_macro(self, formatter, name, args):
    	res=urllib.urlopen('Http://path-to-teamcity:8111/externalStatus.html').read()
	return res

I really love Trac - dont get me wrong - but red just isnt my color. So I made a couple halfhearted moves in the past to style my Trac installation (the one you are looking at atm) a bit but always had a deja vú when stumbling across  Trac: Customizing the Trac Interface as it - in my understanding - ment I had to learn the templating engine used by Trac (Genshi). Being a Python-noob myself investing a lot of time digging through sources wasn't exactly desirable either.

Luckily  Trac-Hacks.org hosts a plugin called  ThemeEnginePlugin which allows replacing the default Trac theme with custom theme-packs. There are a couple pre-prepared theme-packs available at  Trac-Hacks:Themes but half of them look broken (at Trac 0.11) and actually I was quite satisfied to find that the ThemeEnginePlugin allows you to append custom CSS to every Trac-page letting you overwrite whatever suits your needs in the default CSS definitions. Just remember to update your trac.ini (and restart apache afterwards) with

[theme]
enable_css = true

Thanks  Noah Kantrowitz aka coderanger!

Ah yes - just as it took me a while to figure this out back then: inserting arbitrary html in Trac wikipages can be done with

{{{
#!html
HTML HERE
}}}