su was weird today
I can't login into some accounts on some of my GNU/Linux systems. eg. Because some of them are service accounts with no login shell, or simply because it's impolite logging-in to other peoples accounts.
But I needed to know whether one specific account was member of a group. Using
sudo that's trivial.
sudo -u $USERNAME groups
Using su thou requires to also specify -p (aka. --preserve-environment).
su $USERNAME -p -c groups
Not hard either, but a bit unintuitive, especially when the error message just
says: This account is currently not available.