#! perl -slw
use strict;

open F, '>junk.log' or die $!;
print F 'From calling program via F';
close F;
system( 'perl -le"print q[This goes via STDOUT]; print STDERR q[This goes via STDERR];" 1>>junk.log 2>&1' );
open F, '>>junk.log' or die $!;
print F 'From calling program via F';
close F;

__END__
P:\test>type junk.log
From calling program via F
This goes via STDERR
This goes via STDOUT
From calling program via F