TeX Live默认目录情况：
TEXDIR (the main TeX directory):
!! default location: /usr/local/texlive/2015
!! is not writable or not allowed, please select a different one!
TEXMFLOCAL (directory for site-wide local files):
/usr/local/texlive/texmf-local
TEXMFSYSVAR (directory for variable and automatically generated data):
/usr/local/texlive/2015/texmf-var
TEXMFSYSCONFIG (directory for local config):
/usr/local/texlive/2015/texmf-config
TEXMFVAR (personal directory for variable and automatically generated data):
~/.texlive2015/texmf-var
TEXMFCONFIG (personal directory for local config):
~/.texlive2015/texmf-config
TEXMFHOME (directory for user-specific files):
~/texmf