I know I can disallow a particular package in Debian by appending
Package: *x11* Pin: release Pin-Priority: -1
But how can I do that for a virtual package like
httpd? I'd like to disallow installation of all packages that provide this virtual
httpd but the one selected by me. Is there a (simple) way to do this?
The reason: recently, an automatic
apt-get dist-upgrade removed
nginx and installed
lighttpd instead, because some other package (
phppgadmin AFAIR) depended on
httpd and something
nginx started depending on in that update was not installable. I'd really like the whole upgrade to fail in this case, rather than put the http service down. Also: is it possible to make a package "uninstallable"? That would be a good solution, too.