'Pre-check to make sure connection works and that
we can call sudo without a password'

def precheck(self):

    result = 0
    info('***    Checking    servers\n')
    for server in self.servers:
        ip = self.serverIP[server]
        if ((not server) or (server == 'localhost')):
            continue
        info(server, '')
        dest = ('%s@%s' % (self.user, ip))
        cmd = ['sudo', '-E', '-u', self.user]
        cmd += (self.sshcmd + ['-n', dest, 'sudo    true'])
        debug('    '.join(cmd), '\n')
        (_out, _err, code) = errRun(cmd)
        if (code != 0):
            error(('\nstartConnection:    server    connection    check    failed    to    %s    using    command:\n%s\n' % (server, '    '.join(cmd))))
        result |= code
    if result:
        error('***    Server    precheck    failed.\n***    Make    sure    that    the    above    ssh    command    works    correctly.\n***    You    may    also    need    to    run    mn    -c    on    all    nodes,    and/or\n***    use    sudo    -E.\n')
        sys.exit(1)
    info('\n')
