Easiest way to "link" two items

Setup, Configuration and Use Items & Sitemaps
1

What is the easiest way to link to channels, so that changes of Item A get reflected to Item B? For example I have a light switch that has a status LED and would like to link it to the light that it switches. I am using 2 Items there to keep my items file more clean, I could of course directly connect it to the main channel but this keeps my configuration simpler as I have the switches in a seperate file.

Of course I found (Why) is linking two items complex? already, which uses rules (and that would have been my first approach aswell), is there a simpler way to do it though, if I remember correctly I read about a "bind"or link binding a while ago?

2

I think it should be as easy as described by some of the examples in that topic, so just something like

when ItemA changed
then
    ItemB.sendCommand(ItemA.state)
end

The issues mentioned in that topic are related to a function that you ideally shouldn’t use anymore.

At the same time, Follow Profiles might be useful for you, but that really depends on your specific case.

https://www.eclipse.org/smarthome/documentation/development/bindings/profiles.html#followprofile

3

It’s probably worth clarifying that you are talking about linking two devices, rather than just two OH Items.

If these devices are compatible technology e.g. both zwave or both KNX it is invariably better to link them directly, and just let OH eavesdrop on the action. But of course that is not always possible.

This thread has a fairly extensive explore of using follow profile and possible pitfalls.