Comment 27 for bug 1767817

Same problem with a fresh install of Ubuntu 18.10, with Gnome Files/Nautilus 3.26.4.
Tracker is not installed by default. I had to install it afterward. Works fine in command line into the terminal. But this is not enough.

With Gnome Tweak, menu "Plug-ins", Tracker Search (Integrates tracker-search into the gnome-shell desktop)" is shown with an alert sign (⚠). It cannot be activated.

Is that the problem ?

(I installed, from Ubuntu software, the other plug-in "Tracker search provider (Provides tracker search results in overview)".
I checked with Gnome Tweak, it is activated. Then, search with the "Activities Overview" provides 2 categories of search results, "Files" with 5 results on the file name, and "tracker-needle", with 5 results on the full text. Results are presented at the speed of light, type-as-you-go style wished by @William. But this limitation to 5 results is not very convenient, and once away from the Overview and back, the search results are lost. You have to retype your search query all over again…)

@Mordi I installed Gnome Documents. It does present full text search results, but limited to the documents in the formats it deals with ((pdf, docx, odt…), but, strangely not for the plain text documents…

So the only way so far to do complete plain text search with tracker, is to use the terminal. Very strange, since MacOS as well as Windows do this very well with their file managers. (And Ubuntu used to do it before 17.10 at the time of Unity.)

I share the opinion of @bdr529 and @sojusnik that this lack of easy Full text search is ridiculous, and that it should work out of the box. This is a high priority bug.