echo -n "" > /server/tomcat/logs/catalina.out ==>要加上"-n"参数，默认情况下会"\n"，也就是回车符

du -h /server/tomcat/logs/catalina.out

使用echo命令清空tomcat日志文件测试实例:

[root@zdz ~]# echo -n "" > /server/tomcat/logs/catalina.out

[root@zdz ~]# du -h /server/tomcat/logs/catalina.out

0 /server/tomcat/logs/catalina.out