Perl无法尾部旋转日志文件

Question

I am using property based filters of rsyslog to send specific logs to seperate file where those logs will be parsed using perl.

This is my rsyslog entry

$template SPLIT,"/home/shivam/hello-%$YEAR%%$MONTH%%$DAY%%$HOUR%%$MINUTE%"
:msg, contains, "hello" -?SPLIT

So rsyslog will create separate files for logs coming after every minute. Files will be created like this hello-201505281139 .

My perl script to parse these files is

use strict;
use warnings;
use POSIX qw(strftime);

my $date = strftime "%Y%m%d%H%M", localtime;
my $file = '/root/defer-'.$date;
open(my $fh,'<',$file) or die "unable to open file $!\n";

while(1) {
    while(my $line = <$fh>){
                    print "$date\n";
                    print "$line";
            }
    sleep(2);
    unless ($date == strftime "%Y%m%d%H%M", localtime) {
            close($fh);
            $date = strftime "%Y%m%d%H%M", localtime;
            $file = '/root/defer-'. $date;
            system("touch $file");      
            open(my $fh,'<',$file) or die "unable to open file $!\n";

    }
}

In unless block i am checking that if minute has changed then i close previous file and open new file. The reason i am creating new file from script and not waiting for rsyslog to create file is that the frequency of logs coming is not that much. So i create file and just start reading on it in hope that when any new log will come i will be able to read that.

But what is happening is that i am able to create new file but not able to read anything from that file.

This is what i am getting as warning

readline() on closed filehandle $fh at test.pl line 14.

Line 14 in my code is this line while(my $line = <$fh>){

I am not able to see anything wrong in my code. Please suggest what is the mistake.

Answer 1

You have two different $fh lexical (my) variables,

So instead declaring new one

open(my $fh,'<',$file) or die "unable to open file $!\n";

keep using previously declared one,

open($fh,'<',$file) or die "unable to open file $!\n";