Clear browser history from terminal

This article also contains info on how to delete browser stuff (history, cache, downloads) from command line.
I've never done this for opera but ~/.opera contains download.dat, cookies4.dat and a cache4 folder. So, I presuma its just a matter of deleting these. However, can't see where the history is kept.
In any event, I don't believe I'm ever going to badly need to do this.