log4j:ERROR setFile(null,true) call failed. java.io.FileNotFoundException: ./logs/flume.log (Permission denied) 

百度之后说权限不足扫描不到这个log文件。
我又去root用户下执行了一次刷出一推exec /home/hadoop/app/jdk1.8.0_201/bin/java -Xmx20m -cp '/home/hadoop/app/apache-flume-1.6.0-cdh5.7.0-bin/conf:/home/hadoop/app/apache-flume-1.6.0-cdh5.7.0-bin/lib/*:/home/hadoop/app/hadoop-2.6.0-cdh5.7.0/etc/hadoop:/home/hadoop/app/hadoop-2.6.0-cdh5.7.0/share/hadoop/common/lib/activation-1.1.jar:/home/hadoop/app/hadoop-2.6.0-cdh5.7.0/share/hadoop/common/lib/apacheds-i18n-2.0.0-M15.jar:/home/hadoop/app/hadoop-2.6.0-cdh5.7.0/share/hadoop/common/l这样的直接就挂了。