Install fish shell in ubuntu

run command:

sudo apt-add-repository ppa:fish-shell/release-3
sudo apt-get update
sudo apt-get install fish

set fish as default shell

chsh -s /usr/bin/fish
or
chsh -s $(which fish)

install oh my fish
https://github.com/oh-my-fish/oh-my-fish

curl -L https://get.oh-my.fish | fish

set agnoster theme

omf theme agnoster

add newline agnoster