Bug#175937: Acknowledgement (apt: 'does not manipulate the state of the system' wording)
P.S. as a double caution to messing up my system
while experimenting, I used both -s and avoided being root.
$ apt-get -o Dir::Etc::Preferences=preferences \
-s install libc6
E: Could not open lock file /var/lib/dpkg/lock - open (13 Permission denied)
E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?
well, If I weren't going to change the system then why can't i not be root?