module Kernel
  
  # Override raises an error if _cmd_ returns a non-zero exit status.
  # Returns stdout + stderr if _cmd_ succeeds.  Note that these are simply concatenated; STDERR is not inline.
  def ` cmd
    stdout, stderr = ''
    
    begin
      status = Open4::popen4(cmd) do |pid, stdin_stream, stdout_stream, stderr_stream|
        stdout = stdout_stream.read
        stderr = stderr_stream.read
      end
      raise stderr.strip if !status.success?
    rescue Exception => e
      raise "'#{cmd}' failed with: '#{e.message}'"
    end
    
    return stdout + stderr
  end
  
  alias_method :system!, :system
  
  # Override raises an error if _cmd_ returns non-zero exit status.
  # Returns true if _cmd_ succeeds. system!() preserves standard subshell handling (no exceptions; returns false on fail)
  def system cmd
    `#{cmd}`
    return true
  end
  
end