onetwothreefour

##</code><code>##

  #! /usr/bin/perl -w
  use strict;

  if (open FILE, '+<io.txt')
  {
    seek FILE, 3, 0;
    print FILE 'xxx';

    seek FILE, 3, 0;
    my $input = '';
    sysread FILE, $input, 3;
    print "read in '$input'\n";

    close FILE;
  }