SHELL

install fish ubuntu

$ sudo apt-add-repository ppa:fish-shell/release-3
$ sudo apt-get update && sudo apt-get upgrade
sudo apt-get install fish
sudo chsh -s /usr/local/bin/fish

To get back to bash, use:
sudo chsh -s 'which bash'

install cute fish on ubuntu

sudo apt install -y git devscripts build-essential cmake ninja-build
sudo apt install -y qtbase5-dev qtquickcontrols2-5-dev libkf5networkmanagerqt-dev modemmanager-qt-dev debhelper extra-cmake-modules libkf5kio-dev libkf5screen-dev libqt5sensors5-dev qtdeclarative5-dev qttools5-dev qttools5-dev-tools libxcb-icccm4-dev qtbase5-private-dev kwin-dev libkdecorations2-dev libqt5xdg-dev libdbusmenu-qt5-dev libxcb-ewmh-dev libicu-dev libxcb-randr0-dev libsm-dev libxcb-xfixes0-dev libxcb-damage0-dev libxcb-composite0-dev libxcb-shm0-dev libxcb-util-dev libxcb-image0-dev libxtst-dev libpulse-dev libpolkit-qt5-1-dev libpolkit-agent-1-dev libqt5x11extras5-dev

mkdir -p ~/Downloads/cutefish
cd ~/Downloads/cutefish

git clone https://github.com/cutefishos/libcutefish.git
cd libcutefish
dpkg-buildpackage -uc -us -b

cd ~/Downloads/cutefish
git clone https://github.com/cutefishos/fishui
cd fishui
dpkg-buildpackage -uc -us -b

cd ~/Downloads/cutefish
git clone https://github.com/cutefishos/kwin-plugins
cd kwin-plugins
dpkg-buildpackage -uc -us -b

cd ~/Downloads/cutefish
git clone https://github.com/cutefishos/launcher
cd launcher
dpkg-buildpackage -uc -us -b

cd ~/Downloads/cutefish
git clone https://github.com/cutefishos/qt-plugins
cd qt-plugins
dpkg-buildpackage -uc -us -b

cd ~/Downloads/cutefish
git clone https://github.com/cutefishos/wallpapers
cd wallpapers
dpkg-buildpackage -uc -us -b

cd ~/Downloads/cutefish
sudo apt-get install ./*.deb

cd ~/Downloads/cutefish
git clone https://github.com/cutefishos/dock
cd dock
dpkg-buildpackage -uc -us -b

cd ~/Downloads/cutefish
git clone https://github.com/cutefishos/filemanager
cd filemanager
dpkg-buildpackage -uc -us -b

cd ~/Downloads/cutefish
git clone https://github.com/cutefishos/settings
cd settings
dpkg-buildpackage -uc -us -b

cd ~/Downloads/cutefish
git clone https://github.com/cutefishos/statusbar
cd statusbar
dpkg-buildpackage -uc -us -b

cd ~/Downloads/cutefish
git clone https://github.com/cutefishos/core
cd core
dpkg-buildpackage -uc -us -b

cd ~/Downloads/cutefish
sudo apt-get install ./*.deb

## no debian directory
# cd ~/Downloads/cutefish
# git clone https://github.com/cutefishos/calculator
# cd calculator

## no debian directory
# cd ~/Downloads/cutefish
# git clone https://github.com/cutefishos/icons
# cd icons