RT，但是.xls文件可以预览，系统是CentOS 7，装在虚拟机上。
seafevents.log如下
[2016-12-14 10:05:31,608] [DEBUG] start to fetch task <type: doc, id: 372bcb2140f2af61db4bb664e200c75399b94b79>
[2016-12-14 10:05:31,621] [DEBUG] start to convert task <type: doc, id: 372bcb2140f2af61db4bb664e200c75399b94b79>
[2016-12-14 10:05:35,644] [WARNING] error when invoking libreoffice: Verbosity set to level 3
DEBUG: Connection type: pipe,name=seafilepipe;urp;StarOffice.ComponentContext
Input file: /tmp/tmpWDjI4S.doc
Using office base path: /usr/lib64/libreoffice
Using office binary path: /usr/lib64/libreoffice/program
Selected output format: Portable Document Format [.pdf]
Selected office filter: writer_pdf_Export
Used doctype: document
[2016-12-14 10:05:35,644] [WARNING] failed to convert <type: doc, id: 372bcb2140f2af61db4bb664e200c75399b94b79> to pdf
[2016-12-14 10:05:35,644] [DEBUG] removing temporary document /tmp/tmpWDjI4S.doc