看到个模块 File::Bidirectional ，分享下~

x9x9

记得之前论坛有人发帖寻求从文件末尾向前反着读取文件的方法，这个模块对读取日志等大文件应该有用。读取过程中还可以随时切换读取方向。

http://search.cpan.org/~kianwin/ ... le/Bidirectional.pm

1. use File::Bidirectional;
   
2.     my $file = "/var/log/large_file";
   
3. 
   
4.     # Object interface
   
5. 
   
6.     # start from the last line
   
7.     my $fh = File::Bidirectional->new($file, {origin => -1})
   
8.         or die $!;
   
9. 
   
10.     # read backwards until point of interest
    
11.     while (my $line = $fh->readline()) {
    
12.         last if $line =~ /RECORD_START/;
    
13.     }
    
14. 
    
15.     # switch directions
    
16.     $fh->switch();
    
17. 
    
18.     # read forwards until point of interest
    
19.     while (my $line = $fh->readline()) {
    
20.         last if $line =~ /RECORD_END/;
    
21.     }
    
22. 
    
23.     # Tied Handle Interface
    
24. 
    
25.     local *F;
    
26.     tie *F, "File::Bidirectional", $file, {origin => 1}
    
27.         or die $!;
    
28. 
    
29.     while (my $line = <F>) { ... }
    
30. 
    
31.     (tied *F)->switch();

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