Re: runMPgraphicstrue produces undefined figure

[Sanjoy Mahajan <sanjoy@mrao.cam.ac.uk>]

> Check your log file for
>
> systems         : system commands are enabled

Thanks, that was the problem.  It was saying 'disabled' instead.  The
fix was to change /etc/texmf/texmf.cnf to enable write18.  The
shell_escape line has to be set to 't' rather than 'f', i.e.:

 shell_escape = t

Actually, on my system (Ubuntu, a Debian derivative), changing the
texmf.cnf file directly is not a good idea.  Instead one should change
the same line in /etc/texmf/texmf.d/95NonPath.cnf and then run
'update-texmf' as root to generate the texmf.cnf file.

Warning: If you've enabled 'shell_escape', then don't run *TeX on
untrusted files, in case they do anything malicious like 'rm -fr /'.

Also now I see how I got fooled into thinking that write18 was already
enabled.  The one-line tex file from metafun-s.pdf contains
\immediate\write18{echo It works}.  When run it produces an "It works"
whether or not write18 is enabled.  If disabled:

(./3.tex
echo It works
 )

which made me think that all was okay.  If enabled you get this:

 \write18 enabled.
(./3.texIt works
 )

-Sanjoy

`Never underestimate the evil of which men of power are capable.'
         --Bertrand Russell, _War Crimes in Vietnam_, chapter 1.