[amitprasad]

This is heavily language runtime dependent — there’s nothing that fundamentally stops you from doing anything during the phase between jumping to an entry point and the main()

[abnercoimbre]

Indeed the craziest among us occasionally abuse this fact, so long as the compiler implementation lets us.

[Animats]

Right. This tends to come up with packages, which just by virtue of being loaded, set up to do something such as log, print, catch errors, or phone home to something.