Append path to $PATH in fish shell on mac & linux

The best way I have found to persistently add a path to your $PATH is

set-U fish_user_paths $fish_user_paths ~/path/name

This prepends to $PATH. And since it's persistent, the path stays in $PATH on shell restarts.

It's more efficient than putting a command in your config.fish to modify your $PATH, because it only runs once compared to running on every shell restart.

The variable fish_user_paths is intended to be set by the user¹, as stated by ridiculousfish, the maintainer of fish.

Option 2:

Add the line below to the file ~/.config/fish/config.fish:

set PATH $HOME/MAVProxy $PATH