flume 安裝成功後啟動可能會遇到如下異常。

問題：
log4j:WARN No appenders could be found for logger (org.apache.flume.lifecycle.LifecycleSupervisor).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info. 

解決：
問題原因是因為 -c 沒有找到路徑，將啟動命令修改為

nohup /root/apache-flume-1.7.0-bin/bin/flume-ng agent -c  conf -f /root/apache-flume-1.7.0-bin/conf/flume-conf-mysql.properties -n agent1 &
 
啟動成功

[[email protected] apache-flume-1.7.0-bin]#   /root/apache-flume-1.7.0-bin/bin/flume-ng agent -c  conf -f /root/apache-flume-1.7.0-bin/conf/flume-conf-mysql.properties -n agent1  
Info: Sourcing environment configuration script /root/apache-flume-1.7.0-bin/conf/flume-env.sh
Info: Including Hive libraries found via () for Hive access
+ exec /root/jdk1.8.0_181/bin/java -Xmx20m -cp '/root/apache-flume-1.7.0-bin/conf:/root/apache-flume-1.7.0-bin/lib/*:/lib/*' -Djava.library.path= org.apache.flume.node.Application -f /root/apache-flume-1.7.0-bin/conf/flume-conf-mysql.properties -n agent1