启动elasticsearch的时候报了如下错误：
Starting elasticsearch: Exception in thread “main” java.lang.IllegalStateException: Could not load plugin descriptor for existing plugin [ik.tgz]. Was the plugin built before 2.0?
Likely root cause: java.nio.file.FileSystemException: /data/esplugins/ik.tgz/plugin-descriptor.properties: Not a directory
at sun.nio.fs.UnixException.translateToIOException(UnixException.java:91)
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:102)
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:107)
at sun.nio.fs.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:214)
at java.nio.file.Files.newByteChannel(Files.java:361)
at java.nio.file.Files.newByteChannel(Files.java:407)
at java.nio.file.spi.FileSystemProvider.newInputStream(FileSystemProvider.java:384)
at java.nio.file.Files.newInputStream(Files.java:152)
at org.elasticsearch.plugins.PluginInfo.readFromProperties(PluginInfo.java:87)
at org.elasticsearch.plugins.PluginsService.getPluginBundles(PluginsService.java:378)
at org.elasticsearch.plugins.PluginsService.<init>(PluginsService.java:128)
at org.elasticsearch.node.Node.<init>(Node.java:158)
at org.elasticsearch.node.Node.<init>(Node.java:140)
at org.elasticsearch.node.NodeBuilder.build(NodeBuilder.java:143)
at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:178)
at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:270)
at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:35)
Refer to the log for complete error details.
[FAILED]
解决方法：
从报错信息第二行可以看出data/esplugins/ik.tgz/plugin-descriptor.properties: Not a directory，说明没找到这个文件。cd到data/esplugins/下，看到有两个文件，一个是之前下载的ik.tgz，一个是解压完的ik，系统将ik.tgz当成了需要的文件了，但这并不是一个目录，所以把ik.tgz删掉，让系统能够找到ik就可以了。