我正在尝试从mongoDB导出JSON文件。如果我不使用 --dbpath 选项，则记录正在导出。但是，如果我使用 dbpath，它会显示为：
C:\mongodb\bin>mongoexport --db aman --collection saved --dbpath D: --out aman.json 导出 0 条记录
2015-02-02T20:32:37.922+0530 [tools] dbexit:
2015-02-02T20:32:37.925+0530 [tools] shutdown: going to close listening sockets...
2015-02-02T20:32:37.925+0530 [tools] shutdown: going to flush diaglog...
2015-02-02T20:32:37.927+0530 [tools] shutdown: going to close sockets...
2015-02-02T20:32:37.927+0530 [tools] shutdown: waiting for fs preallocator...
2015-02-02T20:32:37.928+0530 [tools] shutdown: closing all files...
2015-02-02T20:32:37.929+0530 [tools] closeAllFiles() finished
2015-02-02T20:32:37.930+0530 [tools] shutdown: removing fs lock...
2015-02-02T20:32:37.930+0530 [tools] dbexit: really exiting now