Execute shell commands and raise if it fails

command.rb

class Command
  attr_accessor :command, :stdout, :stderr, :process

  class Error < RuntimeError
    def initialize(command)
      error = "command failed"
      error << " ($?=#{command.process.exitstatus})" if command.process
      error << ": #{command.command_string}"
      error << "\n\nOUTPUT:\n\n#{command.stdout}" if command.stdout && !command.stdout.empty?

      super error
    end
  end

  def initialize(*command)
    @command = command.flatten
    yield self if block_given?
  end

  def run
    self.stdout  = %x{#{command_string} 2>&1}
    self.process = $?
  end

  def command_string
    command.join(' ')
  end

  def system_or_raise
    puts "+ #{command_string}"
    system(*command)
    self.process = $?
    return self if $?.success?

    raise Command::Error, self
  end

  def run_or_raise
    run
    return self if process.success?

    raise Command::Error, self
  end

  def capture
    run_or_raise.stdout
  end

  def self.capture(*cmd)
    new(*cmd).capture
  end

  def self.system_or_raise(*cmd)
    new(*cmd).system_or_raise
  end
end