Solved can qt4 be considered stable in Linux(Fedora,ubuntu,CentOS..)?
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Many years ago, I bought a qt3 commercial version.
Later, Troll Tech released version 4, then sold to Nokia.
Then, Nokia modified it a bit for its favor and released version5. qt4 was then changed to use LGPL.Not long after this, I somewhat had an impression that
Qt library was sold to Microsoft, which modfied it for
the similar reason and released version 6.Then I googled to find this Qt Library 'official site'
I am totally confused now.Simply put, is qt5 also LGPL licensed?
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@wij2 Check https://www.qt.io/licensing/ and https://www.qt.io/download
And read https://en.wikipedia.org/wiki/Qt_(software) if you want to really know the history of Qt.
Actually it isn't hard to find the official Qt site: https://www.qt.io/developers/
Yes, Qt is available under GPL, LGPL and commercial license. -
To add to @jsulm and short version:
Trolltech was acquired by Nokia
Digia acquired what was Trolltech from Nokia
Digia made a spinoff named The Qt Company with what was Trolltech
Microsoft bought the handset division of Nokia, they never touched Trolltech at any point in time. -
@jsulm OK. Thanks for the information. I think I need first
understand more about qt5 before porting my programs and
buying license. -
@SGaist Thanks for clarifying the ownership, though I still
don't fully understand. -
@wij2 You don't understand what?
Qt is an open source project, licensed under LGPL (partly GPL) and a commercial license. The commercial license is sold by The Qt Company, which is fully independent of Nokia and Microsoft.
Also, there is the Qt-KDE contract, which assures there will always be an open-source Qt version available.
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@wij2 Whether you need a license depends on whether you can fulfil the LGPL license (or need better support from Qt Company). If you can you don't need a commercial license even for proprietary software using Qt.
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@aha_1980 Good to hear that "there will always be an open-source Qt version available".
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@jsulm About half of my programs are open-soure, another
half (compiled executables) are for sell. In both cases, no
modification of qt library is made.
So, I don't need commercial license for the LGPL licensed part
of qt library,right? How to deal with the GPL licensed part? -
@wij2 said in can qt4 be considered stable in Linux(Fedora,ubuntu,CentOS..)?:
How to deal with the GPL licensed part?
If you use GPL licensed modules (i.e. QtCharts) in your program, you need to make it GPL too. Otherwise you need a commercial license.
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@aha_1980 Thanks again. I think I get correct informations
now. Since this is my first time in this forum, how should I do
to make this questioning 'solved' from 'unsolved'? -
@wij2 The should be a button "Topic Tools" below your first post, from there select "Mark as Solved"
Thanks!