Write a file to /etc/cron.d to schedule a command
            env is a dict containing environment variables you want to set in the file
            name will be used as the name of the file

def add_cron(self, name, command, minute="*", hour="*", mday="*", month="*", wday="*", who="root", env=None):
        """
        Write a file to /etc/cron.d to schedule a command
            env is a dict containing environment variables you want to set in the file
            name will be used as the name of the file
        """
        if minute == 'random':
            minute = str(random.randrange(60))
        if hour == 'random':
            hour = str(random.randrange(24))
        fp = open('/etc/cron.d/%s' % name, "w")
        if env:
            for key, value in env.items():
                fp.write('%s=%s\n' % (key, value))
        fp.write('%s %s %s %s %s %s %s\n' % (minute, hour, mday, month, wday, who, command))
        fp.close()