Just open the file before starting the download, then print the downloaded chunk into it in the callback: 
#!/usr/bin/perl
use strict;
use warnings;

use LWP::UserAgent;

my $url = 'http://www.example.com';
my $file = 'myfile.exe';

my $ttlDown = 0;
my $ua = LWP::UserAgent->new;

open my $out, '>', $file or die "$file: $!";

my $resp = $ua->get(
    $url,
    ':content_cb' => sub {
        my ($data, $response) = @_;
        my $size = $response->content_length;
        $ttlDown += length $data;
        printf STDERR "%7.1f KB of %7.1f (%5.1f%%)\n",
            $ttlDown / 1024.0, $size / 1024.0, $ttlDown * 100.0 / $siz
+e;
        print {$out} $data;
    },
);
close $out;

[download]
($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

[download]

In reply to Re: Appending downlad file LWP by choroba
in thread Appending downlad file LWP by Anonymous Monk

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