Example Homebrew formula for a Go command-line (CLI) binary

binary.rb

class Binary < Formula
  desc ""
  homepage ""

  head do
    url "", branch: "main"

    depends_on "[email protected]" => :build if build.head?
  end

  bottle :unneeded

  option "without-completion", "Do not install shell completion"
  
  depends_on OS.linux? ? :linux : :macos

  def install
    if build.head?
      ENV["CGO_ENABLED"] = "0"
      ENV["GOGC"] = "off"

      ENV.prepend_create_path "PATH", "#{HOMEBREW_PREFIX}/bin"
      ENV.prepend_create_path "PATH", buildpath/"bin"

      cd buildpath do
        branch = Utils.safe_popen_read("git", "rev-parse", "--abbrev-ref", "HEAD").strip
        package = "#{head.url.delete_prefix("https://").delete_suffix(".git")}/pkg/version"

        binary_version =
          File.readlines("Makefile").grep(/^VERSION.*[0-9.]+/) do |l|
            l.split("=")[1].strip.tr('"', "")
          end[0] += "-#{branch}"

        ldflags = %W[
          -s -w
          -X #{package}.GitBranch=#{branch}
          -X #{package}.GitRevision=#{version.commit}
          -X #{package}.Version=#{binary_version}
        ].join(" ")

        system "go", "build", *std_go_args(ldflags: ldflags)

        unless build.without? "completion"
          output = Utils.safe_popen_read("#{bin}/", "completion", "bash")
          (bash_completion/"").write output

          output = Utils.safe_popen_read("#{bin}/", "completion", "zsh")
          (zsh_completion/"_").write output

          output = Utils.safe_popen_read("#{bin}/", "completion", "fish")
          (fish_completion/".fish").write output
        end
      end
    end

    if OS.mac? && MacOS.version >= :catalina
      if /com.apple.quarantine/.match?(Utils.safe_popen_read("xattr #{bin}/"))
        (bin/"").chmod 0755
        begin
          system "xattr", "-d",
                          "com.apple.quarantine",
                          bin/""
        ensure
          (bin/"").chmod 0555
        end
      end
    end

    prefix.install_metafiles
  end

  def caveats
    <<~EOS
    EOS
  end

  test do
    assert_predicate bin/"", :exist?
    system "", "--help"
  end
end