1、修改$ZOOKEEPER_HOME/bin目录下的zkEnv.sh文件
   ZOO_LOG_DIR指定想要输出到哪个目录，
   ZOO_LOG4J_PROP，指定INFO,ROLLINGFILE的日志APPENDER.

     54 if [ "x${ZOO_LOG_DIR}" = "x" ]
     55 then
     56     ZOO_LOG_DIR="/usr/zookeeper-3.4.12/logs"
     57 fi
     58 
     59 if [ "x${ZOO_LOG4J_PROP}" = "x" ]
     60 then
     61     ZOO_LOG4J_PROP="INFO,ROLLINGFILE"
     62 fi

2、修改$ZOOKEEPER_HOME/conf/log4j.properties文件
   zookeeper.root.logger的值与前一个文件的ZOO_LOG4J_PROP保持一致
   该日志配置是以日志文件大小轮转的
   如果想要按照天轮转，可以修改为DaliyRollingFileAppender.

      1 # Define some default values that can be overridden by system properties
      2 zookeeper.root.logger=INFO, ROLLINGFILE
      3 zookeeper.console.threshold=INFO
      4 zookeeper.log.dir=.
      5 zookeeper.log.file=zookeeper.log
      6 zookeeper.log.threshold=DEBUG
      7 zookeeper.tracelog.dir=.
      8 zookeeper.tracelog.file=zookeeper_trace.log
      9 
     10 #
     11 # ZooKeeper Logging Configuration
     12 #
     13 
     14 # Format is "<default threshold> (, <appender>)+
     15 
     16 # DEFAULT: console appender only
     17 log4j.rootLogger=${zookeeper.root.logger}
     18 
     19 # Example with rolling log file
     20 #log4j.rootLogger=DEBUG, CONSOLE, ROLLINGFILE
     21 
     22 # Example with rolling log file and tracing
     23 #log4j.rootLogger=TRACE, CONSOLE, ROLLINGFILE, TRACEFILE
     24 
     25 #
     26 # Log INFO level and above messages to the console
     27 #
     28 log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
     29 log4j.appender.CONSOLE.Threshold=${zookeeper.console.threshold}
     30 log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
     31 log4j.appender.CONSOLE.layout.ConversionPattern=%d{ISO8601} [myid:%X{myid}] - %-5p [%t:%C{1}@%L] - %m%n
     32 
     33 #
     34 # Add ROLLINGFILE to rootLogger to get log file output
     35 #    Log DEBUG level and above messages to a log file
     36 #log4j.appender.ROLLINGFILE=org.apache.log4j.RollingFileAppender
     37 log4j.appender.ROLLINGFILE=org.apache.log4j.DailyRollingFileAppender
     38 log4j.appender.ROLLINGFILE.Threshold=${zookeeper.log.threshold}
     39 log4j.appender.ROLLINGFILE.File=${zookeeper.log.dir}/${zookeeper.log.file}
     40 
     41 # Max log file size of 10MB
     42 log4j.appender.ROLLINGFILE.MaxFileSize=10MB
     43 # uncomment the next line to limit number of backup files
     44 #log4j.appender.ROLLINGFILE.MaxBackupIndex=10
     45 
     46 log4j.appender.ROLLINGFILE.layout=org.apache.log4j.PatternLayout
    47 log4j.appender.ROLLINGFILE.layout.ConversionPattern=%d{ISO8601} [myid:%X{myid}] - %-5p [%t:%C{1}@%L] - %m%n
     48 
     49 
     50 #
     51 # Add TRACEFILE to rootLogger to get log file output
     52 #    Log DEBUG level and above messages to a log file
     53 log4j.appender.TRACEFILE=org.apache.log4j.FileAppender
     54 log4j.appender.TRACEFILE.Threshold=TRACE
     55 log4j.appender.TRACEFILE.File=${zookeeper.tracelog.dir}/${zookeeper.tracelog.file}
     56 
     57 log4j.appender.TRACEFILE.layout=org.apache.log4j.PatternLayout
     58 ### Notice we are including log4j's NDC here (%x)
     59 log4j.appender.TRACEFILE.layout.ConversionPattern=%d{ISO8601} [myid:%X{myid}] - %-5p [%t:%C{1}@%L][%x] - %m%n