Are the OSX Mavericks tags visible from the command line? For example, suppose I have a directory structure such as

/Users
    /tlehman
        /Math
            algebraic_varieties.tex [tagged: Math, Documentation]
            projective_geometry.pdf [tagged: Math]
        /Development
            visualize_surfaces.py   [tagged: Math, Programming]
            solve_polynomials.scm   [tagged: Math]
    /guest
        /Desktop
            welcome.rtf             [tagged: Documentation]
/Volumes
    /USBKey
        assignments_for_may.txt     [tagged: Math]
        using_LaTeX.pdf             [tagged: Documentation]


From the command line, is there a way I can use ls (or something like it) to display all the files tagged as "Math"?

EDIT: I made a tool called tfind that does this: https://github.com/tlehman/bin/blob/master/tfind
Yes, you can find files that have a given user tag using mdfind.

Create a file and assign it a a custom tag in Finder.

Then go in a terminal; you will find it with:

mdfind "kMDItemUserTags == Math || kMDItemUserTags == Programming"


or 

mdfind "kMDItemUserTags == Math &amp;&amp; kMDItemUserTags == Programming"


See also -onlyin aFolder to restrict the search.

I didn't check how complex these boolean expressions can be, but these two examples work.

You can pipe the output to ls like this:

mdfind "kMDItemUserTags == mathTag || kMDItemUserTags == anotherTag" \
| while read f; do ls "$f"; md5 "$f"; done


Also, mdfind has an option "-0" 

    -0                Use NUL (``\0'') as a path separator, for use with xargs -0.


which can be practical with nasty filenames.