#   JAVA_OPTS       (Optional) Java runtime options used when any command
#                   is executed.
#                   Include here and not in CATALINA_OPTS all options, that
#                   should be used by Tomcat and also by the stop process,
#                   the version command etc.
#                   Most options should go into CATALINA_OPTS.

简单来说就是 Java options的缩写，在Tomcat的启动脚本中定义了这个环境变量，用于指定JVM运行时的一些参数，但是Java中时没有这个环境变量的，Java中的有一个JAVA_TOOLS_OPTS,用于指定Java提供的一些工具的参数