True instant sync via Dropbox I want to have my todo.txt file synchronized on PC and Android via a cloud service in both ways and instantly on change. Let's call this true instant sync. Unfortunately, I have not found a good solution yet and I don't understand why.
My setting: Markor to edit todo.txt on Android, todo-txt script to edit todo.txt on my Linux PC, official Dropbox client on both Android and PC.
In order to get true instant sync, I tried FolderSync and Autosync for Dropbox. However, I think that neither of these apps does what I want flawlessly and their precise function is not really documented. For example, Autosync for Dropbox has the options &quot;autosync&quot;, &quot;instant upload&quot;, &quot;clever detection of changes&quot; (available in the pro version) and one can also set synchronization in given time intervals, all independently of each other. What do these options do precisely? FolderSync seems to support synchronization in time intervals only, which is not what I want.
I imagine that a true instant sync solution should work as follows:

There is an interrupt whenever something is written in the shared folder .
The interrupt is associated to the sync client, which sends the information about changed files to the sync server immediately.
The sync client pings the sync server whenever its network address changes.
When another sync client uploads something to the sync server, the sync server broadcasts the information about changed files to all sync clients.
There is an interrupt whenever a packet from the sync server is received.
The interrupt is associated to the sync client which updates the local files immediately.

Questions:

How do 1--6 differ from the reality and what are the problems? Aren't the interrupts 1 and 5 already implemented on the system level?
Can I configure Autosync for Dropbox or FolderSync (+ Tasker) so that I get true instant sync which was defined above?
Do you know any other solution for true instant sync?

Thanks!
AFAIK, true instant sync (as in first para of your question) , isn't possible using Dropbox, for reasons mentioned in answer here. If Dropbox itself doesn't permit, you can't force it through either apps you tried (I tried and have the pro version of both these apps).

My need was to have a real time sync across Android and PC (Linux and Windows). The only app I could find was from standard notes. The Android app on Play Store is marked beta but don't let that discourage you. It works perfectly well on Android, Linux and Windows for real time sync.

Only thing left is Dropbox sync - if you go in for pro version of standard notes, you can install an extension, that provides daily updates to Dropbox, and obviously isn't real time. But then your files are synced across platform in real time, so updation in Dropbox may not really matter, unless you have other reasons. I haven't tried this extension because I stopped using Dropbox.


As far as real time sync goes this ticks all the boxes except via Dropbox. You don't need to go in for extended (pro) version, if you decide to cut off Dropbox or use either of the apps you tried for periodic sync.