/usr/share/texmf-texlive/metapost/support/charlib/twiddle is in texlive-metapost 2009-15.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 | % $Id: ~=,v 1.2 2004/09/19 21:47:11 karl Exp $
% Public domain.
vardef C.~eq(expr n) =
save p;
picture p; p="~"infont n;
addto p also "-"infont n shifted(0,-.15*fontsize n);
p enddef;
|