[luatex] \pdfshellescape

[David Carlisle]

The manual lists \pdfshellescape (which used to be 0 1 or 2 depending
if shell escape was allowed or not) as having been dropped as it can
be implemented in lua.

Is there a recommended implementation of this?

I'd hoped to just see a lua value in the status library or some place
set to 0,1,2 as before (or even a \pdfvariable type thing) but it
seems that the only options are to

look at
kpse.var_value("shell_escape") -- for texmf.cnf settings
texconfig.shell_escape -- for lua initialization settings and
arg array for the commandline
and re-do the merging of these to determine whether os.execute is
allowed or restricted?

or to try running os.execute and testing the result?

 but I was looking to avoid calling os.execute if it was prevented by
the current settings.


any hints welcome:-)

David