How to know the version of your current OSM installation
From OSM Public Wiki
Since Release FOUR, in order to know the version that you have installed you only need to search the osm-devops package installed in your system, since osm-devops is the package used to drive installations:
dpkg -l osm-devops ||/ Name Version Architecture Description +++-======================-=================-=====================-===================================== ii osm-devops 4.0.1-1 all
In case you only installed separate stacks (e.g. elk_stack, pm_stack, etc.), you could end with a newer version of the osm-devops package. Then you can search the python-osmclient package as a way to know your current version of OSM:
||/ Name Version Architecture Description +++-======================-=================-=====================-===================================== ii python-osmclient 4.0.1-1 all