Hello Anonymous Monk,

I don’t see how the code you gave in your original question can be what you are really using, since you have:

...
open (FILE, ">data.txt") or die "can't open file: $!";

my $weather_data = do "data.txt";
...
[download]

which first opens the file for writing — thereby truncating it! — and only then reads in its (now empty) contents.

In any case, it is simpler (and therefore less error-prone) to read and write the file in wholly separate steps. Here is a script which does that:

#! perl
use strict;
use warnings;
use Data::Dumper;
use Date::Format;

{
    my $file         = 'data.txt';
    my $today        =  get_timezone();
    my $weather_data =  do $file;

    ${ $weather_data->[0]{xml_api_reply}{weather} }{report_date} = { '
+-data' => $today };

    open(my $out, '>', $file) or die "Cannot open file '$file' for wri
+ting: $!";
    print $out Dumper($weather_data);
    close($out)               or die "Cannot close file '$file': $!";
}

sub get_timezone
{
    $ENV{'TZ'} = 'America/New_York';

    return time2str('%m-%d-%Y @ %H:%M:%S', time);
}
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This outputs:

$VAR1 = [
          {
            'xml_api_reply' => {
                                 '-version' => '1',
                                 'weather' => {
                                                'report_date' => {
                                                                   '-d
+ata' => '08-20-2012 @ 18:50:16'
                                                                 },
                                                '-row' => '0',
                                                'current_conditions' =
+> {
                                                                      
+    'icon' => {
                                                                      
+                '-data' => '/ig/images/weather/mostly_cloudy.gif'
                                                                      
+              },
                                                                      
+    'temp_f' => {
                                                                      
+                  '-data' => '70'
                                                                      
+                },
                                                                      
+    'temp_c' => {
                                                                      
+                  '-data' => '21'
                                                                      
+                },
                                                                      
+    'wind_condition' => {
                                                                      
+                          '-data' => 'Wind: E at 7 mph'
                                                                      
+                        },
                                                                      
+    'condition' => {
                                                                      
+                     '-data' => 'Mostly Cloudy'
                                                                      
+                   },
                                                                      
+    'humidity' => {
                                                                      
+                    '-data' => 'Humidity: 65%'
                                                                      
+                  }
                                                                      
+  }
                                              }
                               }
          }
        ];
[download]

as required.

Hope that helps,