I am having a strange problem when trying to run script via CGI. The code is below and when run as the www-data user at the console the script runs fine. There is no errors in any of the apache logs and there is no errors to screen. Can anyone suggest anything?

#!/usr/bin/perl

use diagnostics;
use warnings;
use strict;
use Expect;
use CGI::Carp qw( fatalsToBrowser );

$|=1;

print "Content-type: text/html\n\n";

my $timeout = 10;
my $user = "mysqladmin";
my $pass = "mysqlpassword";
my $database = "items";
my $backup_path = '/tmp/b2.sql';
my $su_user = "anotheruser";
my $su_password = "password";


# Build su command and env
my $cmd = "su -s /bin/sh";
my $run = "$cmd $su_user -c \"mysqldump -v -u $user --password=$pass $
+database > $backup_path\"";

# Check output on screen - remove when live.
print $run;
print "<br/>";

my $exp = Expect->spawn($run) or die "Cannot spawn command \n";

$exp->expect($timeout, ["Password:"]);
$exp->send("$su_password\n");
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