If you are on a shared hosting platform where you do not have full administrative access to the web server, this could be a challenge, but what you want is documented here for the Apache web server, for example.
It's a (rather broad) web server administration question, rather than a MediaWiki question, and seems beyond the scope of what people could feasibly help you with here without more specifics.
As far as fixing absolute URLs within the wiki, the proper way to do it, as I'm sure you know, is to use [[wikilinks]]
, or the localurl:
or fullurl:
magic words, if for some reason you needed more control over the URL than regular wikilinks provide. Both of those let you get an absolute URL for resources on the wiki without hard-coding anything (that you would need to change later if you're ever in this situation again). You could simply search-and-replace all of the articles with the absolute URLs within the wiki interface itself, or do a SQL UPDATE
query on the underlying database to fix them.
There is also pywikibot, which is a Python solution for doing things like this, but requires programming (even more so than SQL queries).
Hope that helps. A little.