-X exclude-file The specified file contains fnmatch(3) patterns
matching files to be excluded from the specifica-
tion, one to a line. If the pattern contains a `/'
character, it will be matched against entire path-
names (relative to the starting directory); other-
wise, it will be matched against basenames only.
Comments are permitted in the exclude-list file.
ls -lo, and also chflags(1)) and finally any optional soft or hard links the file might have.

I made a script from Dru Lavigne book BSD HACKS.From the mtree() man page:
Code:-X exclude-file The specified file contains fnmatch(3) patterns matching files to be excluded from the specifica- tion, one to a line. If the pattern contains a `/' character, it will be matched against entire path- names (relative to the starting directory); other- wise, it will be matched against basenames only. Comments are permitted in the exclude-list file.
Note: The "exclude-file" is not the file to be excluded, it's a text file in which you list the files you want to exclude. I think that if you write "unbound.log" in a line, that's enough.