Important note. How do you close a file descriptor on a process? You attach to it in gdb, and run the following command:
call close(filedes)
where filedes is the descriptor number.
20160813/http://stackoverflow.com/questions/5987820/how-to-close-file-descriptor-via-linux-shell-command
Now, this is an interesting link. It clearly demonstrates (at the time of visit) the imperfection of the StackOverflow website. And, it shows how sometimes, you must actually read further in order to get the correct information.
20160813/http://stackoverflow.com/questions/323146/how-to-close-a-file-descriptor-from-another-process-in-unix-systems