求助，装了几个虚拟机搞hadoop，重启虚拟机后namenode和datanode只能开启一会会，再开就开不了了。用jps查看进程也找一样没有。出错的日志如下：

STARTUP_MSG:   build = Unknown -r Unknown; compiled by 'hadoop' on 2016-03-08T03:44Z
STARTUP_MSG:   java = 1.8.0_151
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2018-02-10 20:22:00,801 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: registered UNIX signal handlers for [TERM, HUP, INT]
2018-02-10 20:22:00,809 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: createNameNode []
2018-02-10 20:22:02,358 INFO org.apache.hadoop.metrics2.impl.MetricsConfig: loaded properties from hadoop-metrics2.properties
2018-02-10 20:22:03,290 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Scheduled snapshot period at 10 second(s).
2018-02-10 20:22:03,290 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: NameNode metrics system started
2018-02-10 20:22:03,292 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: fs.defaultFS is file:///
2018-02-10 20:22:04,368 FATAL org.apache.hadoop.hdfs.server.namenode.NameNode: Failed to start namenode.
java.lang.IllegalArgumentException: Invalid URI for NameNode address (check fs.defaultFS): file:/// has no authority.
        at org.apache.hadoop.hdfs.server.namenode.NameNode.getAddress(NameNode.java:425)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.getAddress(NameNode.java:415)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.getRpcServerAddress(NameNode.java:466)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.loginAsNameNodeUser(NameNode.java:566)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:586)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:764)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:748)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1441)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1507)
2018-02-10 20:22:04,389 INFO org.apache.hadoop.util.ExitUtil: Exiting with status 1
2018-02-10 20:22:04,398 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: SHUTDOWN_MSG:
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SHUTDOWN_MSG: Shutting down NameNode at desk/192.168.125.4