# File lib/polkit.rb, line 6
  def self.polkit_check(perm,user_name)
    raise "invalid user name" if (user_name =~ /\\$/ or user_name.include? "'")
    #get user id
    uid = `id -u '#{user_name}'`
    raise "unknown user" if $? != 0
    polkit_check_uid perm, uid.to_i
  end