Bug#572259: Wishlist: command (or option) to install new version of package only if was already installed

[Christian Hudon <chrish@pianocktail.org>]

Package: apt
Version: 0.7.26
Severity: wishlist

Hi,

I've been wishing more than once for a version of the "install" command
that works as follows: it installs the new version of the package only
it said package was already installed on the computer. If the package
was not installed, it does nothing.

This is not very useful for a single computer, but it can be really
useful when administering multiple computers when they don't all have
exactly the same set of packages installed on them (because the
computers are used in different roles, some don't have a GUI installed,
etc.) Let's say I want to rush install a new version of a package
(because of an important security update, or because it fixes a problem
a user reported, etc.). Right now, I have to figure out on which
computers said package is installed, and only run "apt-get install foo"
on those computers. With the option I'm proposing, I could just run on
all computers "apt-get install --only-upgrade foo", and the right thing
would get done on each computer. It's even more convenient if one has a
program set up to run a command via ssh on all computers (like I do).

Thanks for considering this. It would be very helpful to me (and to
other sysadmins, I'm sure).

  Christian