sub pid_file_cleanup
{
  my ($ind,@temp_files) = @_;
#       An implicit argument is environment variable $pid_file_cleanup_debug.
#    If set, this program does not delete any files, but prints the ones it 
#    would have deleted
#	Explicit arguments are:
#	  1) A "temp indicator"; a string whose presence in a file spec
#	     means that the file is to be treated by this routine.
#	     Often a pid.
#	  2) An array of filenames to be considered for cleanup
###
#  Clean up temp files (does not do temp directories)
#	We could just delete the ones in @temp_files, but that would be
#    too easy.  Idea is that we'd like the files to stay around a while
#    in case we want to look at them, but delete them if they aren't looked
#    at.  Rather than trying to save a list of exactly what's eligible for
#    deletion, we apply the following algorithm:
#	1) Only look at files in @temp_files
#	2) Of those, only look at the ones with this proc's PID in them
#	   Assumption is that presence of PID is indicator that file really
#	   is temporary & that a bunch of them might exist.
#	   Further assumption is that PID only appears once (fails safe-
#	   no such files will be deleted unless PIDs have recycled)
#	3) Logically replace PID with *
#	4) Look at those files, and delete the ones that haven't been 
#	   accessed in 7 days.  Use access date to prolong life of those
#	   that have been looked at after creation... which are probably 
#	   the ones we REALLY want to save!
  
  local $thisdir = "";
  local $debug = $ENV{"PID_FILE_CLEANUP_DEBUG"};
  local @del_files;
#    local DIR;  Investigate how to localize this
  my ($dir,$before_ind,$after_ind);
  my ($ind,@temp_files) = @_;
  
  if ($debug) {open(DEBUG,">/tmp/pid_file_debug_$$") || die}
#  Loop for those files w/PID in them.  Sort so all files in a directory
#  are together.
  foreach (    sort(  grep(/$ind/,@temp_files)  )    )  {

    $debug && print DEBUG "temp file ... $_\n";
#      ?=/ means don't include the last /
    ($dir) = m"(.*(?=/))";
    ($before_ind,$after_ind) = /(.*)$ind(.*)/;
    $debug && print DEBUG "dir = $dir; before = $before_ind; aft = $after_ind\n";

    if ($dir eq "") {
      $dir = ".";
    } else {
#	Be sure that PID is in file spec, not just directory
#	(test is that if whole directory does not appear before PID, do
#	next loop iteration).  While we're at it, save the file spec portion
#	(stuff after directory)
      ($before_ind !~ /$dir(.*)/) && next
      $file_before_ind = $1;
    }
    
#	Conceptually, following logic is
#	  opendir
#	  find files matching
#	  proc_dir those files
#	  closedir
#	Actual logic attempts to avoid extra opens and closes since we
#	expect many files in each directory
    if ($dir ne $thisdir) {
      $debug && print DEBUG " ... New dir $dir\n";
      &proc_dir;
      undef(@del_files);
      $thisdir = $dir;
      opendir (DIR,$thisdir) || die "Bad opendir : $!\n";
      $start_dir_pos = telldir(DIR);
    }

#     "Rewind" directory file
    seekdir (DIR,$start_dir_pos);
    push (  @del_files, grep(/^$file_before_ind.+$after_ind$/,readdir(DIR))  );
  }
  &proc_dir;
  $debug && close DEBUG;
}
sub proc_dir
{
  my $file;
  if ($thisdir ne "") {
    closedir (DIR);
#     Didn't want to unlink files w/directory open.  Have no
#     particular knowledge about this...
    foreach $file (@del_files) {
      $file = "$thisdir/$file";
      debug && print DEBUG " .. del_file candidate $file\n";
      if (-A $file > 7) {
	if ($debug) { print DEBUG " ... would unlink $file\n"  }
	else { unlink $file }
      }
    }
  }
}
#  Next line needed if you intend to require this file
1;