How to install gvim?

The following worked for me:

run this

sudo apt-get update 

and then run

sudo apt-get install vim-gnome 

On Ubuntu 20.04 (since vim-gnome was removed in 19.10):

sudo apt install vim-gtk3

You'll need to check your sources. I see that libruby1.8 1.8.7.352-2 is available through main while it seems that the newest version you have is: 1.8.6.111-2ubuntu1. This probably means that you dist-upgrade failed or that you still need to update your sources.

$ apt-cache policy libruby1.8
libruby1.8:
  Installed: 1.8.7.352-2
  Candidate: 1.8.7.352-2
  Version table:
 *** 1.8.7.352-2 0
        500 http://archive.ubuntu.com/ubuntu/ oneiric/main amd64 Packages
        100 /var/lib/dpkg/status