From help-octave-request at bevo dot che dot wisc dot edu  Thu Sep 10 13:22:16 1998
Subject: Using Octave in a CGI script
From: John Verzani <verzani at math dot csi dot cuny dot edu>
To: Octave Mailing List <help-octave at bevo dot che dot wisc dot edu>
Date: 10 Sep 1998 10:24:11 -0000


Hello,

I've been working on a CGI script that allows students to use Octave
via the web. To eliminate (I hope!) the possibility of a malicious
student destroying the server it is running on, I am using a package
called sbox which runs the script as a restricted user after issuing a
chroot command. So, in theory, the system calls in octave only have
access to the files I put into the new root directory. Basically I've
put in perl, octave, gnuplot and whatever libraries these need to
run. Everything seems to work well, except for one thing. Gnuplot
doesn't work. I know this has something to do with running gnuplot in
the chroot setting, as the script works when I don't care about
security. If I try running Octave at the command line after a chroot
command I get an error message of this type when trying to plot:

[Levy]# chroot ~octave/ ./octave
Octave, version 2.0.13 (sparc-unknown-linux-gnulibc1).
Copyright (C) 1996, 1997, 1998 John W. Eaton.
This is free software with ABSOLUTELY NO WARRANTY.
For details, type `warranty'.

octave:1> x = 1:5;plot(x)
warning: connection to external plotter (pid = 16515) lost --
warning: please try your plot command(s) again
warning: connection to external plotter (pid = 16516) lost --
warning: please try your plot command(s) again
octave:2> octave:2> warning: connection to external plotter (pid = 16517) lost --
warning: please try your plot command(s) again

octave:2> 

My question is: what things need to be available to octave to create the
subprocess that will allow gnuplot to run as the external plotter?

Thanks for any pointers.

John

....................................................................
.  John Verzani                  mailto:verzani at math dot csi dot cuny dot edu  .
.  Dept. of Mathematics      http://www.math.csi.cuny.edu/~verzani .
.  City University of New York                 tel: (718) 982-3623 .
.  College of Staten Island                    fax: (718) 982-3631 .
....................................................................