Get Involved/Quality/Beta/InstallingBeta1
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Installing 4.9 beta 1 with your distribution packages
Slackware
The packages will be obtainable at http://alien.slackbook.org/ktown/ The instructions for usage will be posted on http://alien.slackbook.org/blog/
Arch Linux
There is a dedicated [kde-unstable] repository. This repo only contains KDE/Calligra beta releases (and their unstable deps); when the stable version is out, the packages are removed.
Installation steps are at: https://wiki.archlinux.org/index.php/KDE#Official_kde-unstable and https://wiki.archlinux.org/index.php/DeveloperWiki:KDE#Users
Fedora
There is an unofficial kde-unstable/kde-testing and a kde-stable repo maintained by Rex Dieter - the place where the newest bits come for already released stuff. But Fedora Rawhide is always the first place for all builds.