Linux dpkg - where does it install to?
Solution 1:
If you are asking where the deb package goes: /var/cache/apt/archives.
If you are asking where the files in the deb package get installed to, then do:
dpkg -L library
Solution 2:
dpkg -L library
(Although, since this isn't a programming related question, it should go on superuser.com or linux.stackexchange.com instead of here.)