/usr/share/texmf-texlive/tex/latex/ is in texlive-latex3 2009-10ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/texmf-texlive/tex/latex/expl3/
/usr/share/texmf-texlive/tex/latex/expl3/expl3.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3basics.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3box.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3calc.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3chk.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3clist.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3doc.cls
/usr/share/texmf-texlive/tex/latex/expl3/l3expan.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3file.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3int.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3intexpr.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3io.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3keys.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3keyval.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3msg.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3names.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3num.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3precom.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3prg.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3prop.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3quark.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3seq.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3skip.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3tl.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3token.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3toks.sty
/usr/share/texmf-texlive/tex/latex/expl3/l3xref.sty
/usr/share/texmf-texlive/tex/latex/keys3/
/usr/share/texmf-texlive/tex/latex/keys3/keys3.sty
/usr/share/texmf-texlive/tex/latex/keys3/keys3opts2.sty
/usr/share/texmf-texlive/tex/latex/mh/
/usr/share/texmf-texlive/tex/latex/mh/breqn.sty
/usr/share/texmf-texlive/tex/latex/mh/cmbase.sym
/usr/share/texmf-texlive/tex/latex/mh/empheq.sty
/usr/share/texmf-texlive/tex/latex/mh/flexisym.sty
/usr/share/texmf-texlive/tex/latex/mh/mathpazo.sym
/usr/share/texmf-texlive/tex/latex/mh/mathptmx.sym
/usr/share/texmf-texlive/tex/latex/mh/mathstyle.sty
/usr/share/texmf-texlive/tex/latex/mh/mathtools.sty
/usr/share/texmf-texlive/tex/latex/mh/mhsetup.sty
/usr/share/texmf-texlive/tex/latex/mh/msabm.sym
/usr/share/texmf-texlive/tex/latex/mh/xfrac.sty
/usr/share/texmf-texlive/tex/latex/xpackages/
/usr/share/texmf-texlive/tex/latex/xpackages/xbase/
/usr/share/texmf-texlive/tex/latex/xpackages/xbase/ldcsetup.sty
/usr/share/texmf-texlive/tex/latex/xpackages/xbase/template.sty
/usr/share/texmf-texlive/tex/latex/xpackages/xbase/xparse.sty
/usr/share/texmf-texlive/tex/latex/xpackages/xtras/
/usr/share/texmf-texlive/tex/latex/xpackages/xtras/l3keys2e.sty