Download and install Golang for Raspberry Pi

.gitignore

go*.linux-armv6l.tar.gz

get_golang.sh

#! /bin/bash

# [get_golang.sh](https://gist.github.com/n8henrie/1043443463a4a511acf98aaa4f8f0f69)
# Download latest Golang release for ARM

set -euf -o pipefail

download_latest_go() {
  local GOURLREGEX='https://.*?/go/go[0-9\.]+\.linux-armv6l.tar.gz'

  echo "Finding latest version of Go for ARM..."
  local url_and_hash="$(wget -qO- https://golang.org/dl | grep --perl-regexp --after-context=5 --max-count=1 "${GOURLREGEX}" )"

  local url="$(echo "$url_and_hash" | grep -oP ${GOURLREGEX})"
  local hash="$(echo "${url_and_hash}" | grep -oP '(?<=<tt>)\w+(?=</tt>)')"

  latest="${url##*/go/}"

  if [  -f "${latest}" ]; then
    echo "File ${latest} exists. Checking against hash: ${hash}"
    if [ "$(sha256sum <"${latest}")" == "${hash}  -" ]; then
      echo "Hash matches"
    else
      echo "Hash mismatch. Please remove the local file and re-run"
    fi
  else
    echo "Downloading latest Go for ARM: ${latest}"
    wget --quiet --continue --show-progress "${url}"
  fi
}

remove_old_go() {
  while true; do
    read -n 1 -p 'Delete old Go from `/usr/local/go`? [Y/n]: ' rm_oldgo
    echo
    case "${rm_oldgo}" in
      Y|y) sudo rm -rf /usr/local/go; break ;;
      N|n) break ;;
      *) : ;;
    esac
  done
}

install_new_go() {
  while true; do
    read -n 1 -p 'Install new Go to `/usr/local/go`? [Y/n]: ' install_newgo
    echo
    case "${install_newgo}" in
      Y|y) sudo tar -C /usr/local -xzf "${latest}"; break ;;
      N|n) break ;;
      *) : ;;
    esac
  done
}

remove_download() {
  while true; do
    read -n 1 -p 'Remove downloaded tarball? [Y/n]: ' rm_tarball
    echo
    case "${rm_tarball}" in
      Y|y) rm -f "${latest}"; break ;;
      N|n) break ;;
      *) : ;;
    esac
  done
}

echo "Starting with $(go version 2> /dev/null || echo "go not installed")"
download_latest_go
remove_old_go
install_new_go
remove_download
echo "Ending with $(go version)"