Performing a search on the Japanese Wikipedia is easy:
http://ja.wikipedia.org/wiki/Special:Search?search=%s
Now, I want to perform a search on all language versions of Wikipedia.
For instance when I search for Alain Pozzuoli, it must list the article in the French Wikipedia (actually the article does not exist in other wikipedias).
With Google I would use: https://www.google.com/search?q=site%3Awikipedia.org+%s
But for privacy reasons I want to avoid that.
How to perform this search using a request to a Wikipedia/Wikimedia server?
Best Answer
If privacy is your only concern, I would suggest you use DuckDuckGo: a search engine that respects their users' privacy and that do not record any user information.
You can use a similar syntax to what you suggested:
https://duckduckgo.com/?q=site%3Awikipedia.org+%s