Unaccessible sudo binaries, non-admin user, no permissions to install, the root is unaccessible BUT…You guessed it…It still installs. 
I swear that I’m serious here, even though this is supposed to be “funny”.
There must be some other “supapowah” binary hidden elsewhere, or what?
Tough to tell exactly what happened with out logs, but Calibre is a flatpak. Flatpak software and runtimes can be installed in user-areas without needing sudo permission. That’s probably why it worked.
https://docs.flatpak.org/en/latest/using-flatpak.html#system-versus-user
You’ll probably find that it created nearly an entire linux filesystem hidden deep within a dot-prefixed folder somewhere under the user’s home directory, then installed its binaries there, and nowhere else.
My fault. I’ve made a mess. I don’t want to explain it all to avoid attacks, but it shouldn’t have installed because even the superuser can’t install (from the terminal) unless proper sudo binaries are given (currently residing in an external drive), and it doesn’t matter if I give it a working password, it should be out of luck without those binaries. I do have a different sudo binary which is not owned by any user and the system relies on it, maybe that’s the case. Nevertheless, this is it.
Ok, I’m an idiot.
Basically, it was asking for the password multiple times for each and every process of the flatpak installation because of the mods I did on the system.
As a test, I typed the password as I was expecting for it to not be able to install as I get an error unless the super-user’s sudo is given.
Nevertheless, the package manager was running as a system process with its own sudo binary and it was enough to start the installation process.
Then, because of the way flatpaks are made, it has asked for permission to install other pieces of the software (I guess it was the locale package) and I didn’t give permission to the process the second time but the process just skipped the files I denied (not knowing as I wasn’t watching the terminal) and the app got partially installed.
Nevertheless, it has shown the “unable to install” notifications but that was only for the part of the package I didn’t allow.
Dunno if this is clear enough.
Anyway, you can delete the post if you want but feel free to show to the world how stupid I can be! XD
LOL
