[root@hadoop101 ~]# /opt/modules/zookeeper-3.4.10/bin/zkServer.sh start-foreground
ZooKeeper JMX enabled by default
Using config: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg
2019-09-19 14:52:29,093 [myid:] - INFO  [main:QuorumPeerConfig@134] - Reading configuration from: /opt/modules/zookeeper-3.4.10/bin/../conf/zoo.cfg
2019-09-19 14:52:29,122 [myid:] - INFO  [main:QuorumPeer$QuorumServer@167] - Resolved hostname: hadoop104 to address: hadoop104/192.168.56.104
2019-09-19 14:52:29,123 [myid:] - INFO  [main:QuorumPeer$QuorumServer@167] - Resolved hostname: hadoop103 to address: hadoop103/192.168.56.103
2019-09-19 14:52:29,123 [myid:] - INFO  [main:QuorumPeer$QuorumServer@167] - Resolved hostname: hadoop102 to address: hadoop102/192.168.56.102
2019-09-19 14:52:29,124 [myid:] - INFO  [main:QuorumPeer$QuorumServer@167] - Resolved hostname: hadoop101 to address: hadoop101/192.168.56.101
2019-09-19 14:52:29,124 [myid:] - INFO  [main:QuorumPeer$QuorumServer@167] - Resolved hostname: hadoop100 to address: hadoop100/192.168.56.100
2019-09-19 14:52:29,124 [myid:] - INFO  [main:QuorumPeerConfig@396] - Defaulting to majority quorums
2019-09-19 14:52:29,134 [myid:101] - INFO  [main:DatadirCleanupManager@78] - autopurge.snapRetainCount set to 3
2019-09-19 14:52:29,135 [myid:101] - INFO  [main:DatadirCleanupManager@79] - autopurge.purgeInterval set to 0
2019-09-19 14:52:29,135 [myid:101] - INFO  [main:DatadirCleanupManager@101] - Purge task is not scheduled.
2019-09-19 14:52:29,150 [myid:101] - INFO  [main:QuorumPeerMain@127] - Starting quorum peer
2019-09-19 14:52:29,171 [myid:101] - INFO  [main:NIOServerCnxnFactory@89] - binding to port 0.0.0.0/0.0.0.0:2181
2019-09-19 14:52:29,172 [myid:101] - ERROR [main:QuorumPeerMain@89] - Unexpected exception, exiting abnormally
java.net.BindException: Address already in use
    at sun.nio.ch.Net.bind0(Native Method)
    at sun.nio.ch.Net.bind(Net.java:433)
    at sun.nio.ch.Net.bind(Net.java:425)
    at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:223)
    at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74)
    at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:67)
    at org.apache.zookeeper.server.NIOServerCnxnFactory.configure(NIOServerCnxnFactory.java:90)
    at org.apache.zookeeper.server.quorum.QuorumPeerMain.runFromConfig(QuorumPeerMain.java:130)
    at org.apache.zookeeper.server.quorum.QuorumPeerMain.initializeAndRun(QuorumPeerMain.java:111)
    at org.apache.zookeeper.server.quorum.QuorumPeerMain.main(QuorumPeerMain.java:78)
[root@hadoop101 ~]#

[root@hadoop100 bin]# jps
1885 QuorumPeerMain
2029 Jps