Golang Linux installer configurator

install-go.sh

#!/usr/bin/env bash

##
# @description Golang Linux installer.
#
# Example usage:
#
#     VERSION=1.17.3 sudo -E bash install-go.sh 
#
# @date 2021-02-18
#
# @author Jay Taylor <outtatime@gmail.com>
#

VERSION="${VERSION:-1.17.3}"

archive_old_go() {
    if [ -d '/usr/local/go' ]; then
        local old_ver
        old_ver="$( \
            /usr/local/go/bin/go version \
                | awk '{print gensub("^go", "", "g", $3)}' \
        )"
        rm -rf "/usr/local/go-${old_ver}"
        mv '/usr/local/go' "/usr/local/go-${old_ver}"
    elif [ -L '/usr/local/go' ]; then
        unlink '/usr/local/go'
    fi
}

install_profile_d() {
    cat << 'EOF' > /etc/profile.d/go.sh 
export GOROOT='/usr/local/go'
export GOPATH="${HOME}/go"

export PATH="${PATH}:${GOROOT}/bin:${GOPATH}/bin"
EOF
}

install_go() {
    local -r archive="go${VERSION}.linux-amd64.tar.gz"

    cd /tmp

    curl -fSLO "https://golang.org/dl/${archive}"

    rm -rf 'go'

    tar -xzf "${archive}"

    mv 'go' "/usr/local/go-${VERSION}"

    ln -s "/usr/local/go-${VERSION}" '/usr/local/go'

    rm -rf "${archive}" "${HOME}/go/pkg/linux_amd64"
}

install_go_main() {
    if [ "${UID}" -ne 0 ]; then
        echo 'ERROR: Must run as root' 1>&2
        return 1
    fi

    archive_old_go
    install_go
    install_profile_d
}

if [ "${BASH_SOURCE[0]}" = "${0}" ] || [ "${BASH_SOURCE[0]}" = '--' ]; then
    set -o errexit
    set -o pipefail
    set -o nounset

    if [ "${1:-}" = '-v' ]; then
        echo 'INFO: Verbose output enabled' 1>&2
        shift
        set -o xtrace
    fi

    install_go_main
fi