#!/usr/bin/perl

use warnings;
use strict;

$|++;
my $main_log = '/tmp/main_log.txt';
my $sub_log  = '/tmp/sub_log.txt';

print "Start: Coming from the script.\n";

open( my $main_log_file, '>>', $main_log )
  or die( "Error: Cannot open $main_log" );

print $main_log_file "Coming from re-opening "
  . "the opened log file.\n\n";

open( my $sub_log_file, '<', $sub_log )
  or die( "Error: Cannot open $sub_log" );
print $main_log_file $_ while( <$sub_log_file> );
close( $sub_log_file );

close( $main_log_file );

<>;      # This will just pause the script.

print "End: Coming from the script.\n";

##</code><code>##

#$ perl test.pl > /tmp/main_log.txt

##</code><code>##

Start: Coming from the script.
Coming from re-opening the opened log file.

Coming from sub-log file.

##</code><code>##

Start: Coming from the script.
End: Coming from the script.
ened log file.

Coming from sub-log file.

##</code><code>##

Start: Coming from the script.
Coming from re-opening the opened log file.

Coming from sub-log file.
End: Coming from the script.