Using `alternatives`

alternatives allows one to select a different executable for a normal command line program, but how does it work?

I'll give an example: I enjoy using NeoVim instead of Vim for different reasons. But there is a nag that I keep hitting: NeoVim executable is called nvim instead of the vim for... Vim.

I could change two different environment variables, VISUAL and EDITOR to nvim, so any application that wants to open an external editor would call NeoVim instead. But, unfortunately, my muscle memory doesn't work with environment variables, so either I keep correcting myself to type nvim instead of vim or I find a way to, when I call vim, it should actually call nvim.

The initial solution is to use aliases, so alias vim nvim (in Fish) would make vim actually run nvim... except when I use sudo, which doesn't expand the alias before its call. The actual solution would be something global, that takes care of this.

And that's what alternatives do.

In my case, what I actually need to do is run the follow command:

sudo alternatives --install /usr/bin/nvim vim /usr/bin/vim 1

What does it do: