I've tried the following command curl --proto '=https' --tlsv1.2 -sSf https://get-ghcup.haskell.org | sh -s install ghcup ghc cabal stack hls but it just runs the standard interactive installer.
clear &&
sudo apt install -y build-essential curl libffi-dev libffi8ubuntu1 libgmp-dev libgmp10 libncurses-dev libncurses5 libtinfo5 &&
curl --proto '=https' --tlsv1.2 -sSf https://get-ghcup.haskell.org | BOOTSTRAP_HASKELL_NONINTERACTIVE=1 BOOTSTRAP_HASKELL_GHC_VERSION=latest BOOTSTRAP_HASKELL_CABAL_VERSION=latest BOOTSTRAP_HASKELL_INSTALL_STACK=1 BOOTSTRAP_HASKELL_INSTALL_HLS=1 BOOTSTRAP_HASKELL_ADJUST_BASHRC=P sh