Install zsh - lightblueseas/linuxstuff GitHub Wiki

You do that with the following command:

sudo apt install zsh

• Verify that zsh is installed:

zsh --version

• Set zsh as your default shell.

chsh -s $(which zsh)

• Verify that zsh set as your default shell.

echo $SHELL

if this gives /bin/bash out than you have to log out from ubuntu or reboot and login again. The first time you open the zsh shell the following screen is shown:

This is the Z Shell configuration function for new users,
zsh-newuser-install.
You are seeing this message because you have no zsh startup files
(the files .zshenv, .zprofile, .zshrc, .zlogin in the directory
~).  This function can help you with a few settings that should
make your use of the shell easier.

You can:

(q)  Quit and do nothing.  The function will be run again next time.

(0)  Exit, creating the file ~/.zshrc containing just a comment.
     That will prevent this function being run again.

(1)  Continue to the main menu.

(2)  Populate your ~/.zshrc with the configuration recommended
     by the system administrator and exit (you will need to edit
     the file by hand, if so desired).

Make your choice and the zsh will start.

You can verify again that zsh is set as your default shell.

echo $SHELL

this should be the output:

echo $SHELL
/usr/bin/zsh

A detailed install description of zsh is on this link install of zsh on oh-my-zsh