{
  my $i = 1; # Function static var... ooooh.
  sub Whatever
  {
    my $select = (defined $_[0]) ? $_[0] : 0;
    my $old_fh;
    local *FH;

    open FH, ">>$file" or die "Failed to open $file, $!";
    if( $select ) { $old_fh = select FH };

    print FH "$i This will go to $file\n";
    print "$i This will go to $file if \$select($select) is true.\n";

    if( $select ) { select $old_fh }
    close FH or die "Failed to close $file, $!";
    $i++;
  }
}

Whatever(0);
Whatever(1); # Now the second print goes to FH.