https://golang.org/dl/

update_golang.sh

update_go() {
	ARCH="$(uname -m | sed 's/^..86$$/386/; s/^.86$$/386/; s/x86_64/amd64/; s/arm.*/arm/; s/aarch64/arm64/')"
	OS="$(uname | tr "[:upper:]" "[:lower:]" | sed 's/mingw/windows/; s/.*windows.*/windows/')"

	# if the $GOROOT environment variable does not exist... 
	if [ -z "$GOROOT" ]
	then
		# if go is installed
		if [ -x "$(command -v go)" ]
		then
			# get the GOROOT from the installed `go env` command
			GOROOT=$(go env GOROOT)
		else
			# GOROOT=/usr/local/go
			GOROOT=/opt/go
		fi
	fi
	
	cd $GOROOT/.. || return
	# go1.16.5
	local GO_VERSION_REMOTE
	GO_VERSION_REMOTE=$(curl "https://go.dev/VERSION?m=text" | head -n1)
	# go version go1.16.5 darwin/arm64
	# to
	# go1.16.5
	local GO_VERSION
	GO_VERSION=$(go version | cut -d " " -f 3)

	# if go is not installed or is installed and outdated
	# https://stackoverflow.com/a/8811800/
	# https://stackoverflow.com/a/2830416/
	# [[ $(go version) != *$GO_VERSION_REMOTE* ]]
	if [ ! -x "$(command -v go)" ] || [ "$GO_VERSION" != "$GO_VERSION_REMOTE" ]
	then
		# macOS
		[ -d ~/.Trash ] && TRASHDIR=~/.Trash
		# Linux, *BSD, Solaris, etc.
		# https://askubuntu.com/a/102106
		# https://unix.stackexchange.com/a/84330
		# https://blogs.oracle.com/solaris/dealing-with-the-trash-v2
		[ -d ~/.local/share/Trash ] && TRASHDIR=~/.local/share/Trash
		# XDG Base Directory
		# https://specifications.freedesktop.org/trash-spec/trashspec-1.0.html
		# https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
		[ -d "$XDG_DATA_HOME/Trash" ] && TRASHDIR=$XDG_DATA_HOME/Trash

		if [ -d go/ ]
		then
			if [ -n "$TRASHDIR" ]
			then
				# move the old go install to the trash
				sudo mv -fv go/ "$TRASHDIR"
			else
				# delete the old go install
				rm -rf go/
			fi
		fi

		echo $GO_VERSION_REMOTE
		echo $OS
		echo $ARCH
		echo "https://dl.google.com/go/$GO_VERSION_REMOTE.$OS-$ARCH.tar.gz"
		# install the latest version of go
		sudo curl "https://dl.google.com/go/$GO_VERSION_REMOTE.$OS-$ARCH.tar.gz" | sudo tar -xzvf -
	else
		echo "Go $GO_VERSION_REMOTE already installed."
	fi
}