Prevent a package to be installed, upgraded, or removed:
aptitude install <package>=
Reconfigure broken package configuration:
It’s a handy tool if you have libapache2-mod-suphp and libapache2-mod-php installed, but you want to remove one of them, because sometimes Apache doesn’t know what you prefer; PHP or SuPHP.
dpkg-reconfigure <package>
Download a package without install:
apt-get -d install <packageName>