带有符号 link 的 Perl File::Tail

Question

背景

我正在使用 File::Tail 来跟踪日志文件符号 link。符号 link 在午夜后更新以包含一个新的日期戳，不幸的是我的脚本在符号 link 更新后没有拖尾新文件。否则，我的脚本会按预期工作。

#!/usr/bin/env perl

use strict;
use warnings;
use utf8;
use Data::Dumper;
use charnames':full';
use Cwd 'abs_path';
use File::Tail;

my $symlink = sub {
my($log) = '/home/user/log'; 
};

my $file=File::Tail->new(
        name=>&$symlink,
        ignore_nonexistant=>1,
        tail=>0,
        interval=>0,
        maxinterval=>1,
        name_changes=>\&$symlink
        ) || warn $!;
print Dumper $file;

while (defined($_=$file->read)) {
# do a bunch of stuff;
}

问题

如何让 perl 遵循更新的符号 link？

Answer 1

来自 File::Tail documentation:

name_changes

Some logging systems change the name of the file they are writing to, sometimes to include a date, sometimes a sequence number, sometimes other, even more bizarre changes.

Instead of trying to implement various clever detection methods, File::Tail will call the code reference defined in name_changes. The code reference should return the string which is the new name of the file to try opening.

Note that if the file does not exist, File::Tail will report a fatal error (unless ignore_nonexistant has also been specified).

所以您的代码引用应该return 新文件的名称，根据您的问题，该文件中有一个日期字符串。也许这样的事情会奏效：

use Path::Tiny;  # file system agnostic path utilty
use Time::Piece; # data utilties

my $symlink = sub {
   my $time = localtime; # a Time::Piece object
   return path(
      '/home/user/log',
      join('', $time->year, $time->mon, $time->mday), 
   )->canonpath;
};

今天这个子会return：/home/user/log20151112

Answer 2

我从 sub

中遗漏了一个 return

my $symlink = sub {
my($log) = '/home/user/log'; 
return $log;
};

现在完美运行！

带有符号 link 的 Perl File::Tail

Perl File::Tail with a symbolic link

perl

tail