在配置mesos master env和mesos slave/agent env文件后运行mesos-start-cluster.sh时，显示正常。命令的输出如下：

root@heron02:/home/yitian# ./mesosinstall/sbin/mesos-start-cluster.sh 
Starting mesos-master on heron02
ssh -o StrictHostKeyChecking=no -o ConnectTimeout=2 heron02 /home/yitian/mesosinstall/sbin/mesos-daemon.sh mesos-master </dev/null >/dev/null
Starting mesos-agent on heron06
ssh -o StrictHostKeyChecking=no -o ConnectTimeout=2 heron06 /home/yitian/mesosinstall/sbin/mesos-daemon.sh mesos-agent </dev/null >/dev/null
Starting mesos-agent on heron07
ssh -o StrictHostKeyChecking=no -o ConnectTimeout=2 heron07 /home/yitian/mesosinstall/sbin/mesos-daemon.sh mesos-agent </dev/null >/dev/null
Everything's started!

但是，当我尝试停止mesos群集并运行mesos stop cluster命令时，显示屏显示错误消息：

root@heron02:/home/yitian# ./mesosinstall/sbin/mesos-stop-cluster.sh 
Stopping mesos-agent on heron06
Stopping mesos-agent on heron07
Stopping mesos-master on heron02
mesos-master: no process found
Everything's stopped!

这意味着mesos主机启动文件。配置文件没有问题，两个代理主机启动成功。此外，mesos-master-env.sh内容为：

# Some options you're likely to want to set:

# export MESOS_log_dir=/var/log/mesos

export MESOS_log_dir=/home/yitian/mesosdata/log
export MESOS_work_dir=/home/yitian/mesosdata/data
export MESOS_ZK=zk://heron01:2181/mesos
export MESOS_quorum=1

mesos slave/agent-env.sh的内容是：

# The mesos master URL to contact. Should be host:port for

# non-ZooKeeper based masters, otherwise a zk:// or file:// URL.

export MESOS_master=heron01:5050
export MESOS_log_dir=/home/yitian/mesosdata/log
export MESOS_work_dir=/home/yitian/mesosdata/run

# export MESOS_isolation=cgroups

问题是mesos主进程无法启动，mesos ui(http://heron01：5050）无法打开。怎么了？