Let's consider an Ubuntu 15.04 installation which takes the whole HD space:
Is it possible to shrink either /dev/sda2 or /dev/sda5 in order to get free space (with a view to install a more recent Ubuntu version and make it bootable)?
I tried with Ubuntu Disks utility and Gparted to no avail.

E: Unable to locate package system-config-lvm– David Sep 16 '17 at 09:27sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu $(lsb_release -sc) universe"was missing. – David Sep 16 '17 at 09:35Software & Updates– heynnema Sep 16 '17 at 14:00