I have 18.04 Ubuntu with Mate.
I looked at Top 15 Open Source Backup Software for Linux
page on Internet and found, that Kbackup fits my needs: it's a tool with tree inspector with checkbox (gnome has ascetic Deja Dup).
https://www.ubuntupit.com/wp-content/uploads/2018/03/Kbackup.jpg
But how can I install it?
Recommended method sudo apt-get install kbackup
doesn't work: there is no such package.
Also I noticed that its package in pre-release freeze status, what does it mean?
Or may be you suggest an alternative?
KBackup
isn't available for Bionic. You'll need to wait for 18.10 which will have KDE Plasma 5.13. Bionic has KDE Plasma 5.12. As for alternatives, see https://askubuntu.com/questions/2596/comparison-of-backup-tools. – DK Bose Oct 16 '18 at 10:20