1  #!/usr/local/bin/perl 
 2    
 3  use strict; 
 4    
 5  my $dirname = 'logdir'; 
 6    
 7  opendir (DIR, $dirname) or die "could not open dir, $!\n"; 
 8  my @files = sort map {"$dirname/$_" } grep { !/^\.+$/ } readdir DIR; 
 9  closedir DIR; 
10    
11  my $it = make_iterator(@files); 
12    
13  while (my $line = $it->()) { 
14    print $line; 
15  } 
16    
17  sub make_iterator 
18  { 
19    my (@datafiles) = @_; 
20    
21    return unless @datafiles; 
22    
23    my $fh = do { local *FH };  
24    while (@datafiles) { 
25      my $file = shift (@datafiles); 
26      (open ($fh, $file)) 
27        ? last 
28        : print STDERR "failed to open $file, $!\n" 
29    } 
30    
31    my $iterator =   
32      sub { 
33        my $line; 
34        return $line if ($line = <$fh>); 
35   
36        while (@datafiles) { 
37          close $fh; 
38          my $file = shift (@datafiles); 
39          unless (open ($fh, $file)) { 
40            print STDERR "failed to open $file, $!\n"; 
41            next; 
42          } 
43          return $line if ($line = <$fh>); 
44        } 
45      return; 
46    }; 
47    return $iterator; 
48  }