Set the Path

When a CGI script runs, it behaves as a separate user, the http daemon. Consequently, it inherents a user envrionment. Typically, this environment is minimal, containing almost no path information, for example. Thus, if you are going to run other software, you must add the path to the script's environment:

$ENV{PATH} .= ":/usr/local/bin:/u/share/bin";

Talking to Maple and Mathematica

#!/usr/local/bin/perl

$ENV{PATH} .=":/usr/local/bin:/u/share/bin";

#get the current process number

$pid = $$;

#open a connection to Maple

$maple = "| maple -q  > maple.$pid";
$maplegif = "maplegif.$pid";
open(MAPLE, $maple) || print STDERR "Maple can't be opened!\n";

#Send commands via print

print MAPLE "print(2 + 3); \n";
print MAPLE
"interface(plotdevice=gif,plotoutput=`$maplegif`,plotoptions=`width=500,height=300`);\n";
print MAPLE
"plot(x^2, x=-2..2);";
print MAPLE "quit;\n";
close(MAPLE);

#Set up some unique file names

$math_in = "math_in.$pid";
$math_out = "math_out.$pid";
$math_ps = "math_ps.$pid";
$math_gif = "math_gif.$pid";

#Construct a batch input file

open(MATH, "> $math_in") || print STDERR "Math can't be opened!\n";
print MATH "4 + 5\n";
print MATH "Display[\"$math_ps\",Plot[x^2, {x,-2,2},DisplayFunction->Identity]];\n";
print MATH "Quit \n";
close(MATH);

#process the file, convert the PS output

system("math -batchinput -batchoutput <$MATH_IN > $math_out");
system("psfix $math_ps | convert - $math_gif");