I dedicate this blog post to all the several tips and tricks I came across the web. I will add the source of the tip/trick also. Maybe you can find more for you on the source that I didn’t add.

VIM Tips & Tricks

When you want to convert some ENV variables to lower… (I needed this to create a vault file in Ansible for the values of some environment values)

ggVGu

Or to Upper case:

ggVGU

Source: https://coderwall.com/p/anvddw/vim-convert-text-to-lowercase-or-uppercase