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why Ubuntu 11.10 32 bit wants to update qt3 and qt4

Asked by Brian Oh

Hi,

I am running Ubuntu 11.10 32 bit, and the update manager wants to update qt3 and qt4 which I have deleted. When I type in QT in Software Manager under Installed, it brings up three Unity 2d items - Launcher, Panel, Places.

I cannot see why QT is required, because any items such as Unity are surely precompiled in the distribution.

Any ideas?

Thanks, Brian

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mycae (mycae) said : 		#1

QT is used by unity2d as a dynamic library, which is a modular method of distributing compiled software [1]. Compilation does not preclude dependencies, owing to dynamic linkage -- this is an important mechanisim in maintaining system security and ensuring bugfixes are distributed to applications in a timely manner.

Unity2D uses functionality provided by qt in its implementation[2] -- hence unity2d cannot function without qt, and thus it is auto-installed as a dependency by your package manager.

[1] https://secure.wikimedia.org/wikipedia/en/wiki/Dynamic_library
[2] http://packages.ubuntu.com/source/oneiric/unity-2d

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Brian Oh (brianoh9999) said : 		#2

Many thanks for the information. It does not appear to explain why everything appears to be working OK on my system, and I have deleted all QT3 and QT4 components, or does it? Cheers, Brian

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Best mycae (mycae) said : 		#3

Unfortunately the software tries to hide a lot of details in the packaging system, likely this is why it appears you do not have a library installed

if you instead use synaptic, or via the terminal with aptitude search lib*qt*, or via apt-cache, you will likely see that you have qt installed.

Try opening a terminal and running

sudo apt-get install aptitude
aptitude search libqt* | grep ^i

to list installed qt packages -- I suspect (but don't know without running the command), that this will produce a non-empty output.

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Brian Oh (brianoh9999) said : 		#4

Hi,
It appears that QT software still exists, so I guess your answer is correct.

eg:
A libqapt-runtime - Runtime components for the QApt library
i A libqapt1 - QApt library package
i A libqca2 - libraries for the Qt Cryptographic Archite
i A libqt4-dbus - Qt 4 D-Bus module
i A libqt4-declarative - Qt 4 Declarative module
i A libqt4-declarative-gestures - Qt 4 gestures QML plugin
i A libqt4-declarative-particles - Qt 4 particles QML plugin
i A libqt4-declarative-shaders - Qt 4 shaders QML plugin
i A libqt4-designer - Qt 4 designer module
i A libqt4-dev - Qt 4 development files
i A libqt4-help - Qt 4 help module
i A libqt4-network - Qt 4 network module

Thanks, Brian

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Brian Oh (brianoh9999) said : 		#5

Thanks mycae, that solved my question.