#!/usr/bin/perl -w

use strict;

local *FILE;

open( FILE, ">log.txt" ) or die "Unable to open log!\n$!\n";

sub print_log {
  my $fh = shift;
  my $message = shift;

  print $fh $message;
}

&print_log( *FILE, "Hello!\n" );

print FILE "All done!\n";

close FILE or die "Unable to properly close log!\n$!\n";