place the latest Go distribution in /opt/golang so we can link to it with alternatives

golatest.bash

#!/usr/bin/env bash

set -euxo pipefail

command -v go &>/dev/null && INSTALLED_VERSION=$(go version | grep -Po '.*go(\s+)?\K\d+\.\d+(\.\d+)\s+linux/.*' | sed -E 's|\s+linux/.*||g')
LATEST_GOLANG=$(wget -qO- "https://go.dev/VERSION?m=text" | grep -Po '^go(\s+)?\K\d+\.\d+(\.\d+)?$')
[[ $LATEST_GOLANG == ${INSTALLED_VERSION:-} ]] && exit 0
sleep 2
cd $(mktemp -d)
LATEST_GOLANG_ARCH=go${LATEST_GOLANG}.linux-$(dpkg --print-architecture).tar.gz
wget -q https://go.dev/dl/${LATEST_GOLANG_ARCH}
sudo mkdir -p /opt/golang/go${LATEST_GOLANG}
if tar -tf ./${LATEST_GOLANG_ARCH} | head -n 1 | grep -q '^go/'; then
    sudo tar -xf ./${LATEST_GOLANG_ARCH} --directory=/opt/golang/go${LATEST_GOLANG} --strip-components=1
else
    sudo tar -xf ./${LATEST_GOLANG_ARCH} --directory=/opt/golang/go${LATEST_GOLANG}
fi
sudo update-alternatives --install /usr/local/go goroot /opt/golang/go${LATEST_GOLANG} 50
sudo update-alternatives --set goroot /opt/golang/go${LATEST_GOLANG}
sudo ln -sfvn /opt/golang/go${LATEST_GOLANG} /opt/goroot
go version