easy version manager for golang, default at `~/bin` for `v1.13.4`

go-versions

#!/usr/bin/env bash
### usage example:$ go-versions 1.13.4

set -e

export GOVERSION="$1"

[[ ! -z "$2" ]] && export LOCAL_BIN="$2"
[[ -z "${LOCAL_BIN}" ]] && export LOCAL_BIN="${HOME}/bin"
[[ ! -d "${LOCAL_BIN}" ]] && mkdir -p "${LOCAL_BIN}"

[[ -z "${GOVERSION}" ]] && export GOVERSION="1.13.4"
[[ -z "${GOOS}" ]] && export GOOS="linux"
[[ -z "${GOARCH}" ]] && export GOARCH="amd64"

export GOROOT="${LOCAL_BIN}/go-${GOVERSION}"

export GO_DIST_URI="https://storage.googleapis.com/golang/go${GOVERSION}.${GOOS}-${GOARCH}.tar.gz"
export FALLBACK_GO_DIST_URI="https://dl.google.com/go/go${GOVERSION}.${GOOS}-${GOARCH}.tar.gz"
export GO_DIST_LOCAL="/tmp/go-${GOVERSION}.tar.gz"

if [[ ! -f "${GOROOT}/bin/go" ]]; then
  set -x
  wget -c -O "${GO_DIST_LOCAL}" "${GO_DIST_URI}"

  if [[ $? -ne 0 ]]; then
    echo "failed to download ${GO_DIST_URI}, trying fallback"
    wget -c -O "${GO_DIST_LOCAL}" "${FALLBACK_GO_DIST_URI}"

    if [[ $? -ne 0 ]]; then
      echo "failed to download ${FALLBACK_GO_DIST_URI}"
      exit 123
    fi
  fi

  tar zxf "${GO_DIST_LOCAL}" -C "${LOCAL_BIN}"

  mv "${LOCAL_BIN}/go" "${GOROOT}"
  set +x

else
  echo "the required Go binary is locally available"

fi

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

echo ""
echo "add following line to your profile:"
echo ""
echo "                 export PATH=\"${GOROOT}/bin:\${PATH}\""
echo ""
echo "or below as advanced helpere, which also provides 'go-defaults' foo to switch version"
echo ""
echo "go-defaults(){"
echo "    local _VERSION=\"\${1:-\${GOVERSION_DEFAULT}}\""
echo "    export GOVERSION=\"\${_VERSION}\""
echo "    export GOROOT=\"\$HOME/bin/go-\${GOVERSION}\""
echo "    export PATH=\"\${GOROOT}/bin:\${PATH}\""
echo "}"
echo "export GOVERSION_DEFAULT=\"1.13.4\""
echo "go-defaults"

######################################