install_homebrew.rb

#!/usr/bin/ruby
#
# Download and execute this script in one-line with no temporary files:
#
#     ruby -e "$(curl http://gist.github.com/raw/323731/install_homebrew.rb)"
#
#
# I deliberately didn't DRY /usr/local references into a variable as this
# script will not "just work" if you change the destination directory. However
# please feel free to fork it and make that possible.
#
# If you do fork, please ensure you add a comment here that explains what the
# changes are intended to do and how well you tested them.
#
# 15th May 2010:
#   Noticed that on a fresh install of 10.6 the default group for 
#   Administrators is admin not staff. In fact no users are in staff so 
#   replaced all references to staff with admin. Tested on 10.6.3.
#
# 30th March 2010:
#   Added a check to make sure user is in the staff group. This was a problem
#   for me, and I think it was due to me migrating my account over several
#   versions of OS X. I cannot verify that for sure, and it was tested on
#   10.6.2 using the Directory Service command line utility and my laptop.
#
#   My assumptions are:
#     - you are running OS X 10.6.x
#     - your machine is not managed as part of a group using networked
#       Directory Services
#     - you have not recently killed any baby seals or kittens
#
# 14th March 2010:
#   Adapted CodeButler's fork: http://gist.github.com/331512
#

module Tty extend self
  def blue; bold 34; end
  def white; bold 39; end
  def red; underline 31; end
  def reset; escape 0; end
  def bold n; escape "1;#{n}" end
  def underline n; escape "4;#{n}" end
  def escape n; "\033[#{n}m" if STDOUT.tty? end
end

class Array
  def shell_s
    cp = dup
    first = cp.shift
    cp.map{ |arg| arg.gsub " ", "\\ " }.unshift(first) * " "
  end
end

def ohai *args
  puts "#{Tty.blue}==>#{Tty.white} #{args.shell_s}#{Tty.reset}"
end

def warn warning
  puts "#{Tty.red}Warning#{Tty.reset}: #{warning.chomp}"
end

alias :system_orig :system
 
def system *args
  abort "Failed during: #{args.shell_s}" unless system_orig *args
end

def sudo *args
  args = if args.length > 1
    args.unshift "sudo"
  else
    "sudo #{args}"
  end
  ohai *args
  system *args
end

def getc  # NOTE only tested on OS X
  system "stty raw -echo"
  STDIN.getc
ensure
  system "stty -raw echo"
end

####################################################################### script
abort "/usr/local/.git already exists!" if File.directory? "/usr/local/.git"
abort "Don't run this as root!" if Process.uid == 0
abort <<-EOABORT unless `groups`.split.include? "admin"
This script requires the user #{ENV['USER']} to be in the admin group. If this
sucks for you then you can install Homebrew in your home directory or however
you please; please refer to the website. If you still want to use this script
then promote your user to be an Administrator using the System Preferences.

EOABORT

ohai "This script will install:"
puts "/usr/local/bin/brew"
puts "/usr/local/Library/Formula/..."
puts "/usr/local/Library/Homebrew/..."

chmods = %w(bin etc include lib sbin share var . share/locale share/man share/info share/doc share/aclocal).
            map{ |d| "/usr/local/#{d}" }.
            select{ |d| File.directory? d and not File.writable? d }
chgrps = chmods.reject{ |d| File.stat(d).grpowned? }

unless chmods.empty?
  ohai "The following directories will be made group writable:"
  puts *chmods
end
unless chgrps.empty?
  ohai "The following directories will have their group set to #{Tty.underline 39}admin#{Tty.reset}:"
  puts *chgrps
end

puts
puts "Press enter to continue"
abort unless getc == 13

if File.directory? "/usr/local"
  sudo "/bin/chmod", "g+w", *chmods unless chmods.empty?
  # all admin users are in admin
  sudo "/usr/bin/chgrp", "admin", *chgrps unless chgrps.empty?
else
  sudo "/bin/mkdir /usr/local"
  sudo "/bin/chmod g+w /usr/local"
  # the group is set to wheel by default for some reason
  sudo "/usr/bin/chgrp admin /usr/local"
end

Dir.chdir "/usr/local" do
  ohai "Downloading and Installing Homebrew..."
  # -m to stop tar erroring out if it can't modify the mtime for root owned directories
  system "/usr/bin/curl -sfL http://github.com/mxcl/homebrew/tarball/master | /usr/bin/tar xz -m --strip 1"
end

ohai "Installation successful!"

if ENV['PATH'].split(':').include? '/usr/local/bin'
  puts "Yay! Now learn to brew:"
  puts
  puts "    brew help"
  puts
else
  warn "/usr/local/bin is not in your PATH"
end