dpkg seems not to 'see' virtual package installed.
 

i experience a problem in ubuntu 10.04 of not being able to install a
third-party deb package with dpkg. And if i install it with ignore
flags afterwards apt wont leave me install anything unless i remove the
third party package . Sorry if not related. I'm a user of dpkg and it
seems to me that maybe the bevahior i see has sth to do either with a
maloformed third party package either with a dpkg strange behavior, and
as i see in that bug report is still unsolved (https://bugs.launchpad.net/ubuntu/+bug/480903)




Analytically my problem:



In my Lucid 10.04 trying to make my canon pixma 3600 work i downloaded
from canon the driver which is the file:

ip3600_debian_printer.tar

and it contains two deb packages:

cnijfilter-common

cnijfilter-ip3600series

and cnijfilter-common-3.00-1.tar.gz


For cnijfilter-common holds:

Depends: libc6 (>= 2.3.4-1), libcup

sys2 (>= 1.2.1), libpopt0 (>= 1.7)


And for the installed libcups2 in lucid 10.04 holds:

Replaces: libcupsys2 (<< 1.3.7-6)

Provides: libcupsys2

Conflicts: libcupsys2 (<< 1.3.7-6)


but:

sudo dpkg -i cnijfilter-common_3.00-1_i386.deb
(translating some errors from greek)

Decompressing cnijfilter-common (από cnijfilter-common_3.00-1_i386.deb)
...

dpkg: dependencies problems prevent configuration of cnijfilter-common:

cnijfilter-common depends from libcupsys2 (>= 1.2.1). But:

Package libcupsys2 in not installed


Why is the last true since the virtual package libcupsys2 is
installed?






thanks



alex prekates

dpkg seems not to 'see' virtual package installed.
 

Hi Alex,

Prekates Alexandros wrote:

> cnijfilter-common depends from libcupsys2 (>= 1.2.1). But:
> Package libcupsys2 in not installed

The meaning of dependencies is spelled out in full in the Debian
policy manual (which is the closest we have to a high-level manual for
dpkg). It says[1]:

If a relationship field has a version number attached, only
real packages will be considered to see whether the
relationship is satisfied

The code agrees[2].

/* If there was no version specified we try looking for Providers. */
if (possi->verrel == dvr_none) {

I believe it would be possible to diagnose this better, though ---
for example: in addition to

cnijfilter-common depends on libcupsys2 (>= 1.2.1)
libcupsys2 is not installed but configs remain

to say something like

libcup2 provides libcupsys2, but virtual packages have no version

If you would like to work on that, I'd be glad ot provide any help
I can.

Regards,
Jonathan

[1] http://www.debian.org/doc/debian-policy/ch-relationships.html#s-virtual
[2] src/depcon.c::depisok


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dpkg seems not to 'see' virtual package installed.
 

στις 13/12/2010 02:04 πμ, O/H Jonathan Nieder Î*γÏ�αψε:
> Hi Alex,
>
> Prekates Alexandros wrote:
>
>
>> cnijfilter-common depends from libcupsys2 (>= 1.2.1). But:
>> Package libcupsys2 in not installed
>>
> The meaning of dependencies is spelled out in full in the Debian
> policy manual (which is the closest we have to a high-level manual for
> dpkg). It says[1]:
>
> If a relationship field has a version number attached, only
> real packages will be considered to see whether the
> relationship is satisfied
>
> The code agrees[2].
>
> /* If there was no version specified we try looking for Providers. */
> if (possi->verrel == dvr_none) {
>
> I believe it would be possible to diagnose this better, though ---
> for example: in addition to
>
> cnijfilter-common depends on libcupsys2 (>= 1.2.1)
> libcupsys2 is not installed but configs remain
>
> to say something like
>
> libcup2 provides libcupsys2, but virtual packages have no version
>
> If you would like to work on that, I'd be glad ot provide any help
> I can.
>
> Regards,
> Jonathan
>
> [1] http://www.debian.org/doc/debian-policy/ch-relationships.html#s-virtual
> [2] src/depcon.c::depisok
>


Thanks very much for the explanation.

So for time being cancelling packages and making them virtual (like
libcupsys2) is an operation that could break dependencies to thirdparty
packages.

I'll try to look at it as soon as i find some time.





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