plot2d in Lisp CGI (was: plot2d output "")

As I wrote, #$plot2d(...)$ (not part of script, just that command from clisp) from root terminal worked, but from my "yigal" user terminal I got "permission denied" error.

All other maxima's command (except plot2d) worked from both terminals, as well as direct execution of "gnuplot", so there is something special with plot2d.

I tryed plot2d to screen and to file (to directory that "yigal" can write in), with format "gnuplot" and "gnuplot-pipes" - the result is same error.

I thought, may be the problem  is in maxima image, so I saved new maxima image, this time from clisp runned by "yigal" user and not by root as I did before. Now I can do plot2d from user terminal and CGI script runned from user terminal works too!

Apache run on my machine as "www-data" user, so I think may be a solution will be to save maxima image as this user, but I don't know right now how to do it.

Anyway, I think, there is something to fix with plot2d function.

Milan Lukic <milan at eskimo.com> wrote: I would try to play with umask, and if that does not help, then
try a Debian user group, say http://lists.debian.org/debian-apache

I was making a tighter security on a linux machine last year and one
of consequences was that I only could run Maxima as root. The fix was
simple, but I can't remember now what did the trick. Sorry for not
being of more help.

Milan

* Yigal Asnis <yigalasnis at yahoo.com> [2007-09-19 00:08:20 -0700]:

> The error in Apache log is "UNIX error 13 (EACCES): Permission denied".
> I tryed to run the script from a console:
> If I log in as root, there is no problem - plot is created.
> If I log in as non-root (my regulary user "yigal") I get the same error as  in Apache log above.
> I  checked the permissions of gnuplot - it can be executed by everyone.
> I tryed to create output file in directory that everyone can write in : [gnuplot_out_file "/tmp/outfile.ps"], but still have the same error.
> Finally, I runned 
> clisp -M -maxima.mem
> from my non-root-user terminal (usually I use root terminal) and tryed 
> #$plot2d (sin(x), [x,-1,1], [gnuplot_term, ps], [gnuplot_out_file "/tmp/outfile.ps"])$
> and still have the same error!
> What else can be wrong with permissions?
> 
> 
> Andrej Vodopivec  wrote: On 9/18/07, Rupert Swarbrick  wrote:
> > On Mon, 17 Sep 2007 13:17:21 -0700 (PDT)
> > Yigal Asnis  wrote:
> >
> > > It turns out that return value of plot2d ("") wasn't
> > > problem. I suppressed it by (progn #$plot2d(...)$
> > > (princ "something I need to print")) but CGI program
> > > still stuck.
> > > If I execute the CGI file from terminal, it works -
> > > plot2d generates plot file and all other output work
> > > as expected.
> > > But if I point to CGI file with browser, the plot file
> > > isn't generated and all commands after plot2d aren't
> > > executed.
> > > I think the problem is calling external function
> > > (gnuplot) from CGI.
> > > I use Apache with mod_cgi on Debian.
> > >
> > > Yigal Asnis
> >
> > Are you on *nix?
> >
> > I don't know much at all about cgi programming in general or with
> > gnuplot in particular, but maybe there's a problem because gnuplot is
> > an X11 program?
> >
> > In particular, try running some random X11 program (gnuplot,xeyes ?)
> > from a console (Ctrl-Alt-F1) on Linux and you'll get a 5 sec. or so
> > wait followed by an error message complaining that it was unable to
> > communicate with the X server (because the DISPLAY variable was not set
> > and it doesn't know who to ask).
> >
> > Running from Apache as a CGI script, your program might have a similar
> > problem. Have you tried running your CGI script via a proper console? I
> > think that would show whether this is the problem.
> 
> gnuplot does not require X to be running. The following produces a ps
> file even from console (you need to set the plot_format to gnuplot,
> the default gnuplot_pipes does not work for me).
> 
> plot2d(sin(x), [x,-5,5], [plot_format, gnuplot], [gnuplot_term, ps]);
> 
> HTH,


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Yigal Asnis

need to solve math problems for the school - try my site (in hebrew) 

math-tool.co.il
       
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