Many systems in Hungary store geographical coordinates in EOV projection. Often, these need to be converted to GPS, which is easier to work with (or… or even more difficult, in some cases I prefer EOV).

More precisely, it is a matter of converting EPSG:23700 (EOV) format to WGS 84

After some research, I found that the easiest, and most easily scriptable way to do this is using PROJ

Installation (on Ubuntu, but there are many other options):

apt install proj-bin

Convert EOV to GPS:

$ echo 651804.2509374797 237667.6262724590 | cs2cs -f "%.10f" EPSG:23700 EPSG:4326
47.4829506012   19.0713855051 0.0000000000