Dpkg

dpkg is the debian package management tool, the basic one that other front-ends such as apt-get and aptitude use. It is also used in Ubuntu.

useful arguments

 * dpkg -s mailx - gets install status of package mailx
 * dpkg -L mailx - lists the files installed package mailx
 * dpkg -S mailx - searches all packages for the file mailx – handy for finding the owner of a file