Ah, thank you for that, it works when I grant execute access to "/" (the actual filesystem restrictions are actually set by a wrapper program, so this isn't an issue). However, I notice that the executed program "aplusb.scm" doesn't inherit stdin/stdout from the calling program, so that now I can enter "1" and "1" from within DrRacket and it prints "2", but when I execute it from the command line all I see is "#<procedure:evaluator>". Is there a way to fix this? <div class="gmail_quote">On Fri, Sep 17, 2010 at 4:00 PM, John Clements <<a href="mailto:clements@brinckerhoff.org">clements@brinckerhoff.org</a>> wrote: <blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> <div class="im"> On Sep 17, 2010, at 12:31 PM, bbi5291 wrote: > Thanks for the tip Eli, that seems like what I'm looking for. I can't actually figure out how to use it for files though; when I write > -------------------- > (make-evaluator 'racket (string->path "aplusb.scm")) > -------------------- > I get the error message > -------------------- > open-input-file: `read' access denied for aplusb.scm" </div>I believe in this case the sandbox is denying you access to read the file. I believe you can equip the sandbox with this privilege, if you like. <div class="im"> > -------------------- > even though I definitely have read access to this file. > If I try > -------------------- > (define aplusb (open-input-file "aplusb.scm")) > (make-evaluator 'racket aplusb) > -------------------- > then the error message is > -------------------- > exception raised by error display handler: directory-exists?: `exists' access denied for /; original exception raised: module: illegal use (not at top-level) </div>Looks to me like the outer error is caused again by your inability to access the file system, in this case because the input port has source locations in that file. The inner error is probably because the evaluator isn't expecting to see a 'module' form here. John </blockquote></div>