Q: How to get the path of all opened spreadsheet documents

Hi,

Request:
In RedHat7, I want to get the path of all opened spreadsheet documents with Java.

What I've done:

1.       I used Runtime.exec(cmd...) with Java code, the 'cmd' was defined with "ps -ef | grep xxx"

->if only one spreadsheet document opened, the returned info list the correct document, I can parse 
it and get the file path

->but if multi spreadsheet documents opened, the returned process still only list the first 
document, I cannot get other documents.
       2.  I also test in bash, it seems "ps -ef" cannot list all files.

So , I want to know is there any other way to do it. such as using UNO service with libreoffice API 
to get it.
Anyone who knows it is much appreciate.

Best Regards
William