install_homebrew, script to install packages on a new machine (extracted from private dotfiles)

homebrew —> cask-core

1password
divvy
dropbox
google-chrome
nvalt
screenflow
skitch
spotify
sublime-text

homebrew —> core

# Stored in `homebrew/` relative to the installation script
ack
autossh
cloc
coreutils
diff-so-fancy
git
gnu-sed
gnu-tar
grep
htop
imagemagick
jq
mas
netcat
pandoc
parallel
pcre
pstree
pv
rbenv
readline
ruby-build
socat
sqlite
the_silver_searcher
tig
tmux
tree
watch

install_homebrew.rb

#!/usr/bin/env ruby

# Installs homebrew packages from groups in homebrew directory

require 'io/console'

# Assumes installation somewhere in a user's home directory
current_dir = File.dirname(File.expand_path(__FILE__))
HOMEBREW_PATH = File.join(current_dir, 'homebrew')

def homebrew_installed?
  system("hash brew")
end

def installed_packages(list_cmd)
  `#{list_cmd}`.split("\n").map {|ea| ea.strip }
end

def load_groups
  Dir.glob("#{HOMEBREW_PATH}/*").map {|ea| File.basename(ea) }
end

def load_packages(group_name)
  File.read(File.join(HOMEBREW_PATH, group_name)).split("\n")
end

# output a command for display and run it
def systemv(cmd)
  warn cmd
  system cmd
end

# Prompt the user to enter Y/n
def yes?
  input = STDIN.getch
  abort if input == "\u0003" # ctrl-c
  ["y", "\n", "\r"].include?(input)
end

def main
  unless homebrew_installed?
    warn "Homebrew not installed."
    warn "Install from instructions at https://brew.sh/"
    abort
  end

  # Any group that starts with "cask" will be installed using
  # `brew cask` instead of plain `brew`
  #
  # Prioritize any group named core
  groups = load_groups.sort_by {|ea| ea == "core" ? " " : ea }
  puts "Found #{groups.size} groups: #{groups.join(", ")}"

  groups.each do |group|
    is_cask = group.start_with?("cask")
    list_cmd    = is_cask ? "brew cask list"            : "brew list"
    install_cmd = is_cask ? "brew cask install --force" : "brew install"

    current_packages = installed_packages(list_cmd)
    group_packages = load_packages(group)

    puts ""
    puts "#{group.upcase} (#{group_packages.size} packages)"
    group_packages.sort.each do |pkg|
      char = current_packages.include?(pkg) ? "✔︎" : "✘"
      puts "#{char} #{pkg}"
    end

    missing_packages = group_packages - current_packages
    if missing_packages.empty?
      puts "All packages installed"
    else
      puts "The following packages are missing from the #{group} group: #{missing_packages.join(", ")}"
      print "Install? [Y/n] "
      if yes?
        puts "Installing..."
        systemv "#{install_cmd} #{missing_packages.join(' ')}"
      end
    end
    puts ""
  end
end

main if $PROGRAM_NAME == __FILE__