What does the following apt-get response mean?

[Tom H]

On Sat, Dec 4, 2010 at 5:38 PM, NoOp <glgxg at sbcglobal.net> wrote:
>
> Just as an added note: Locking a package in Synaptic will not lock/pin
> the package in apt-get. For example; if I downgrade the udisks package
> in Synaptic & lock it, using apt-get upgrade will still offer to upgrade
> the package:
>
> $ sudo apt-get upgrade
> Reading package lists... Done
> Building dependency tree
> Reading state information... Done
> The following packages will be upgraded:
>  udisks
> 1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
> Need to get 212kB of archives.
> After this operation, 0B of additional disk space will be used.
> Do you want to continue [Y/n]?
>
> So, in order to properly pin the package in apt-get, you need to:
>
> $ sudo -s
> # echo udisks hold | dpkg --set-selections
> # exit
> $ sudo apt-get update
> $ sudo apt-get upgrade
>
> and now we find the result of the last:
> $ sudo apt-get upgrade
> Reading package lists... Done
> Building dependency tree
> Reading state information... Done
> The following packages have been kept back:
>  udisks
> 0 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
>
> Seems to me that using Synaptic to 'pin' a package should also result in
> the package being 'pinned' in apt-get as well. If I find time I'll
> rummage aound in launchpad to see if a bug has already been filed, if
> not I'll file one.

Because Synaptic keeps a package's hold/install status in
"/var/lib/synaptic/preferences".