I wonder if (and how) it is possible to always automatically commit a repository once Eclipse is closed?
I didn't find any option in the Eclipse "Team" preferences.
Don't ever do that. Committing should be done when
Moreover, the commit might very well fail if someone else has made a conflicting change, forcing you to update and perhaps made additional changes before trying to commit again.
In short, it's not something that should be automated at the closing of Eclipse (and that's why Eclipse doesn't allow to do it and probably never will).