I've been using dpkg -S <package_name> to list the contents of a package. Sometimes I pipe to grep bin to quickly scan for executables.

I just ran into a case where this didn't work out for me:

$ which virtualenv
$ sudo apt-get install python-virtualenv
Reading package lists... Done
...
Setting up python-virtualenv (1.7.1.2-1) ...
$ which virtualenv
/usr/bin/virtualenv
$ dpkg -S /usr/bin/virtualenv 
python-virtualenv: /usr/bin/virtualenv
$ dpkg -S python-virtualenv | grep bin
$

/usr/bin/virtualenv seems to be provided by python-virtualenv, but isn't listed in the package contents provided by dpkg -S. All the while, passing /usr/bin/virtualenv to dpkg -S returns that the file comes from python-virtualenv. Can you all explain this?