Where can you find the version number of the OS on the KDE desktop.
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If you mean the ISO version number that you used at install, it is in file
/usr/lib/endeavouros-release
.
But as this is a rolling release with constantly updated packages, that version number doesn’t mean very much. It is only the ISO version that you used at install time.
You can find out the version of your KDE Plasma desktop with the following command:
plasmashell --version
EndeavourOS itself does not have a version number, because of its rolling release model. It is not like Debian or 'buntu, where you install a version of it and keep it. On EndeavourOS there is only the “current” version. So, if I installed EndeavourOS two years ago, with an old ISO image, and you installed it yesterday, using the newest ISO image, we are still using the same OS.
The System Information tab of KInfoCenter will provide the versions for Plasma, Frameworks, Qt, and kernel.