These 'datuk' maybe worshiped alone or with 5 or 7 brothers. In Malaysia, You will see many red shrines outside of a Chinese house, factories, beside crossroads, river banks or in construction sites etc.
Unlike other deities, a shrine is only built for a 'datuk' on special requests. When a 'datuk' wished to be worshiped, then it will make its intention know by appearing itself in people's dreams or actual manifestations.
For example: if a worksite has seen frequent accidents or injuries, or the work progress is slow for no apparent reasons; person in charge would employ a medium to ask for reasons. At this time, a spirit would possess the medium and identify itself as a 'datuk' who watched over that location for some years.
In order to stop all mishaps, a shrine must be built and offerings of turmeric sticky rice and curry mutton periodically.
I have some encounters with 'datuk' spirit:
When I was about 10, together with my cousins and uncles went to a small shrine in rubber plantation at night to see some people asking for lucky numbers.
A 'tangki' (medium) was called in for the purpose. It was around midnight and after some chanting, the medium was possessed by a spirit identified itself as 'Datuk Hitam' (black grandpa).
Oddly speaking, after this Datuk Hitam has identified itself, it immediately made roaring sounds as if it was a tiger. Then someone asked: "Can Datuk Hitam gave some lucky numbers?"
Datuk HItam remained roaring for quite a while and opened its mouth: "Now I am hungry, I want to eat first! Give me some raw meat!"
Everyone looked at each other as where on earth can anyone find raw meat?
There was a long silent. The Datuk Hitam became impatient and finally it said: "If there is no meat... I will eat this medium's left hand."
As soon as Datuk Hitam finished its words, it started to chew at the medium's finger making horrible squeaking noises. Almost immediately Datuk Hitam has severed two of the medium's fingers. With its bloody mouth, Datuk Hitam said: "I have not tasted human flesh for 500 years!"
At this point, some of those on lookers rushed to the medium and pressed him onto the ground. They started to slap the medium until the Datuk Hitam which possessed his body left.
The crowd quickly dispersed and no body dares to call up Datuk Hitam at night since that incident. I don't know what had happened to that poor 'tangki' after the awful incident.