Another short note in the series "useful package-manager commands" ;) .
Every serious user of Linux has experienced the problem of a missing shared library when compiling the sources of a third-party program. Now, you may know that you'd need lib64xyz.so.n for a successful compilation, but you may not know which (not installed!) package actually contains this particular library.
I know only two package managers which would deliver this information in a straightforward way:
wajig whichpkg <exact_filename>
(this one needs lynx and fping)
In Archlinux, pacman -Qo only searches local packages, as does OpenSuse's pin. :(