In the VIM editor in UBUNTU, press the arrow keys on the small keyboard, ABCD will appear and the delete button cannot be used.

This situation occurs mainly because the default VIM editor version of UBUNTU is vim tiny. We can change it to vim full to solve this problem. We first delete the original tiny version of the editor, and then install vim full. The specific command is:

sudo apt-get remove vim-common

Delete the original VIM editor version

sudo apt-get install vim

Install the new vim full editor version

Reopen it with the vim editor and you will find that the problem has been resolved.