#start of login.cgi

  open(FILE, ">file.log");
  flock(FILE, 2); # 2 is an exclusive lock
  print FILE "$a:$b:$c\n";
  close FILE;

  #call function
  function ();

#  return 0;
  #end of login.cgi
  -------------------
  ;#start of login.pl

  sub function
  {
  open(FILE, "<file.log");
  flock(FILE, 1); # 1 is a shared lock

  $a = <FILE>;
  print "line: $a\n";
  close FILE;
  #end of login.pl
  1;
}