Newbie "undefined value"

From: Nadine (nadine_at_mail.sdsu.edu)
Date: 10/08/03 

Date: Wed, 08 Oct 2003 10:08:36 -0700

Hello,

I get a "cannot use undefined value as symbol ref at line 45." I have
used strict and -w. I am using CARP. From the command line, my syntax
checks out as OK. From that same command line, if I pass in parameters,
then I get the "undefined value." I thought "strict" would catch all
undefined variables. I am using Perl 5 and Apache.

I had a short script that printed to the browser. Now I am changing it
to print to a file and using parts of Stein's guestbook script. Here is
the resulting script.

#!/usr/bin/perl -w
use strict;
use warnings;
use CGI qw(:standard Carp qw(fatalsToBrowser)); # import shortcuts
use Fcntl qw(:flock); # imports LOCK_EX, LOCK_SH, LOCK_NB

my(
        $DATAFILE,
        $fh, # File Handle
        $TIMEOUT,
        $path_name,
        $path,
        $description,
        $lock_type,
);
        
# give path and name of data file
$DATAFILE="Eval.dat";

my $cgi = CGI->new();
   my $value = $cgi->param( 'keyword' ) || '';

sub write_datafile {
     my $fh = filelock($DATAFILE,1);
     unless ($fh) {
        print strong('Sorry, an error occurred: unable to open file.'),p();
        Delete('action');
        print a({-href=>self_url},'Try again');
        return undef;
     }
}

# List field names in order.
  foreach my $item ( qw(orgclass relevance majorReq course) ) {
       my $value = $cgi->param( $item ) || 0;
         print $fh "$value . |\n";
   }

# Generate web page saying thank you

print $cgi->header,
        $cgi->start_html('Thank You'),
        $cgi->h2('Thank You'),
        $cgi->p("Thank you for your feedback."),
        $cgi->p("Return to ", a({-href=>'http://www-rohan.sdsu.edu/~ssrllab/'},
         "SSRL Lab home page")),
        $cgi->hr({-width=>"100%"}),
        $cgi->end_html;

     unlock($fh);
     1;

sub filelock {
     my $path = shift;
     my $for_writing = shift;

     my ($lock_type,$path_name,$description);

         $lock_type = LOCK_EX;
         $path_name = ">>$path";
         $description = 'writing';
     }

     local($main::msg,$main::oldsig);
     my $handler = sub { $main::msg='timed out';
$SIG{ALRM}=$main::oldsig; };
     ($main::oldsig,$SIG{ALRM}) = ($SIG{ALRM},$handler);
     alarm($TIMEOUT);

     open ($fh,$path_name) or
        warn("Couldn't open $path for $description: $!"), return undef;

     # now try to lock it
     unless (flock ($fh,$lock_type)) {
        warn("Couldn't get lock for $description (" . ($main::msg ||
"$!") . ")");
        alarm(0);
        close $fh;
        return undef;
     }

     alarm(0);
     return $fh;

sub unlock {
     my $fh = shift;
     flock($fh,LOCK_UN);
     close $fh;
}