I ran into an issue recently whereby Webmin caused Apache to tank during what seemed to be a routine package upgrade.
As it turns-out, Webmin uses 'apt-get install -y package-name', instead of 'apt-get upgrade', because the author is unaware of any means by which packages may be upgraded selectively using the latter command.
The details of the issue are described here: https://bugs.launchpad.net/ubuntu/+s...e2/+bug/969426
I scoured the relevant documentation for apt-get and indeed, the Webmin author is correct. There appears to be no facility for upgrading specific packages.
My question to the community is, how does Ubuntu's Update Manager upgrade packages individually? The interface provides a checkbox for each proposed update, and the user is able to pick-and-choose.
If anyone has any insight, it would be most appreciated.