New to Perl - strange behaviour with backticks

I am trying to set up a CGI script that will run two other scripts and
then write a short message back to the webpage. I have this mostly
working, except for one strange issue: after using backticks to read
the stdout from the first script, stdout from the second script is
being printed to the page as if it were printed from the CGI script
that acts as the caller. The behaviour disappears if I comment out
the backticks, but then I can't get the information i need from the
stdout of the first script. The code follows:

#!/usr/bin/perl
use CGI;

print "Content-type: text/html\n\n";
my $query = new CGI;
my $pdbCode = $query->param("pdbcode");
my $scriptPath = "~/Sites/etaserver/bin";
my $rankPath = "~/Documents/Templates/Distance\ Matcher/Data/2006/
Data";
my $pdbPath = "~/Documents/Templates/Distance\ Matcher/Data/
2006/2006pdb90\ ET/$pdbCode";
my $pymolPath = "/sw/lib/pymol-py24/bin/pymol";

my $extractMotifArgs = "perl -I$scriptPath \"$scriptPath/
extractmotif.pl\" \"$pdbPath/$pdbCode.clusters\" \"$pdbPath/
$pdbCode.dssp\" \"$pdbPath/$pdbCode.pdb\" \"$pdbPath/$p
my $motifs = `$extractMotifArgs`;
#my $motifs="1,2,3,4";

if($pdbCode =~ /^\d\w{3}\w?$/ && -e $pdbPath) {
$pdbPath =~ s/\\//g;
my $args = ("$pymolPath -cr $scriptPath/createPyMolImage.py --
$pdbCode \"$pdbPath\" $motifs");
system($args);
if (($? >> 8) == 0) {
print "CreatedImage:".$pdbCode;
} else {
print "Error:Unable to Create image";
}
} else {
print "Error:Unable to find PDB Data\n";
}

This is Perl 5.8.6.

Thank you,
Eric

Re: New to Perl - strange behaviour with backticks

Eric wrote:
> I am trying to set up a CGI script that will run two other scripts and
> then write a short message back to the webpage. I have this mostly
> working, except for one strange issue: after using backticks to read
> the stdout from the first script, stdout from the second script is
> being printed to the page as if it were printed from the CGI script
> that acts as the caller. The behaviour disappears if I comment out
> the backticks, but then I can't get the information i need from the
> stdout of the first script.

Assuming that

system($args);

executes the second script you are talking about, what if you call also
that script using backticks (in void context):

qx($args);



--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl