use strict;
use warnings;

use Config;
print STDERR qq!Perl $^V on $^O arch $Config{archname}\n!;

sub demo {
  my ($s1, $s2) = ('','');
  my $sFormat = "s1='%s' s2='%s'\n";

  open(my $fh1, '>', \$s1) or die "Can't open fh1";
  print $fh1 'Hi Thing One';
  printf STDERR $sFormat, $s1, $s2;
  # => s1='Hi Thing One' s2=''

  open(my $fhSave, '>&', $fh1) or die "Can't save fh1";
  close $fh1;
  open($fh1, '>', \$s2) or die "Can't redirect fh1";
  print $fh1 'Hi Thing Two*Bye Thing Two';
  printf STDERR $sFormat, $s1, $s2;
  # => s1='Hi Thing One' s2='Hi Thing Two*Bye Thing Two'

  # PICK ONE OF TWO OPEN OPTIONS BELOW
  #1#
  #print STDERR "Option 1\n"; open($fh1, '>&', $fhSave)               
+      or die "Can't restore fh1";

  #2#
  #print STDERR "Option 2\n";open($fh1, '>', \ substr($s1, length($s1)
+) )  or die "Can't restore fh1";

  print $fh1 '*Bye Thing One';
  printf STDERR $sFormat, $s1, $s2;

  # OUTPUT FROM OPEN OPTIONS
  #1# => s1='Hi Thing One' s2='Hi Thing Two*Bye Thing Two'
  #2# => s1='Hi Thing One*Bye Thing One' s2='Hi Thing Two*Bye Thing Tw
+o'
}
demo();
exit(0);
[download]

#option 1
  ----------------------------------------·······
 | Perl v5.14.2 on MSWin32 arch MSWin32-x86-multi-thread
 |  s1='Hi Thing One' s2=''
 |  s1='Hi Thing One' s2='Hi Thing Two*Bye Thing Two'
 |  Option 1
 |  s1='Hi Thing One' s2='Hi Thing Two*Bye Thing Two'
  --------------------------------------------------------------------
+---·······
[OK] C:\ulisse\strawberry\perl\bin\perl.exe
  ----------------------------------------·······
 | Perl v5.20.0 on MSWin32 arch MSWin32-x86-multi-thread-64int
 |  s1='Hi Thing One' s2=''
 |  s1='Hi Thing One' s2='Hi Thing Two*Bye Thing Two'
 |  Option 1
 |  s1='Hi Thing One' s2='Hi Thing Two*Bye Thing Two'
  --------------------------------------------------------------------
+---·······
[OK] C:\ulisse\straw5.20-32b\perl\bin\perl.exe
  ----------------------------------------·······
 | Perl v5.16.2 on MSWin32 arch MSWin32-x64-multi-thread
 |  s1='Hi Thing One' s2=''
 |  s1='Hi Thing One' s2='Hi Thing Two*Bye Thing Two'
 |  Option 1
 |  s1='Hi Thing One' s2='Hi Thing Two*Bye Thing Two'
  --------------------------------------------------------------------
+---·······
[OK] C:\ulisse\straw64\perl\bin\perl.exe


#option 2
  ----------------------------------------·······
 | Perl v5.14.2 on MSWin32 arch MSWin32-x86-multi-thread
 |  s1='Hi Thing One' s2=''
 |  s1='Hi Thing One' s2='Hi Thing Two*Bye Thing Two'
 |  Option 2
 |  s1='Hi Thing One*Bye Thing One' s2='Hi Thing Two*Bye Thing Two'
  --------------------------------------------------------------------
+---·······
[OK] C:\ulisse\strawberry\perl\bin\perl.exe
  ----------------------------------------·······
 | Perl v5.20.0 on MSWin32 arch MSWin32-x86-multi-thread-64int
 |  s1='Hi Thing One' s2=''
 |  s1='Hi Thing One' s2='Hi Thing Two*Bye Thing Two'
 |  Option 2
 |  s1='Hi Thing One*Bye Thing One' s2='Hi Thing Two*Bye Thing Two'
  --------------------------------------------------------------------
+---·······
[OK] C:\ulisse\straw5.20-32b\perl\bin\perl.exe
  ----------------------------------------·······
 | Perl v5.16.2 on MSWin32 arch MSWin32-x64-multi-thread
 |  s1='Hi Thing One' s2=''
 |  s1='Hi Thing One' s2='Hi Thing Two*Bye Thing Two'
 |  Option 2
 |  s1='Hi Thing One*Bye Thing One' s2='Hi Thing Two*Bye Thing Two'
  --------------------------------------------------------------------
+---·······
[download]

option 1

perl c:\ulisse\elisheva-demo01.pl
Pe on MSWin32 arch MSWin32-x86-multi-thread
s1='Hi Thing One' s2=''
s1='Hi Thing One' s2='Hi Thing Two*Bye Thing Two'
Option 1
s1='Hi Thing One' s2='Hi Thing Two*Bye Thing Two'


>echo option 2
option 2

>perl c:\ulisse\elisheva-demo01.pl
Pe on MSWin32 arch MSWin32-x86-multi-thread
s1='Hi Thing One' s2=''
s1='Hi Thing One' s2='Hi Thing Two*Bye Thing Two'
Option 2
s1='Hi Thing One' s2='Hi Thing Two*Bye Thing Two'

>perl -v

This is perl, v5.8.8 built for MSWin32-x86-multi-thread
[download]