We are going to assume that nothing is installed on your Ubuntu. When I created this tutorial I installed ohmyzsh on a brand new Intel Nuc.

Install Zsh

sudo apt-get update
sudo apt-get install -y zsh

Install the custom fonts

sudo apt-get install -y powerline fonts-powerline

Install Git

sudo apt-get install -y git

Install ohmyzsh

git clone https://github.com/robbyrussell/oh-my-zsh.git ~/.oh-my-zsh
cp ~/.oh-my-zsh/templates/zshrc.zsh-template ~/.zshrc

Install custom theme

Inside the ~/.zshrc file comment the line ZSH_THEME="robbyrussell" and add this new line just below ZSH_THEME="agnoster".

Change the default shell

chsh -s /bin/zsh

Note: You can still revert and go back to bash using the command chsh -s /bin/bash.

Plugin installation

In case you want syntax highlighting you can install this plugin:

git clone https://github.com/zsh-users/zsh-syntax-highlighting.git "$HOME/.zsh-syntax-highlighting" --depth 1

echo "source $HOME/.zsh-syntax-highlighting/zsh-syntax-highlighting.zsh" >> "$HOME/.zshrc"