Shell Programming and Scripting

perl -ne 'BEGIN {$from="150318 23:40:04" ; $to="150319  1:10:40"; $from=`date -d "$from" +%s`; $to=`date -d "$to" +%s`;} $r=`date -d "$1" +%s` if /^(.*?)\[/; print if ($r <= $to) && ($r >= $from);' file

to=`date "+%y%m%d %H:%M:%S"`
from=`date "+%y%m%d %H:%M:%S" -d "-30 minutes"`

perl -ne '
    BEGIN{$from=qx(date -d -30min +%s); $to=qx(date +%s)}
    $r=qx(date -d "$1" +%s) if /^(.*?)\[/;
    print if ($r <= $to) && ($r >= $from);
' file

#!/usr/bin/perl

# this is not tested since I do not have any valid log files.
use strict;
use warnings;
use POSIX qw(strftime);

my $now = time;
my $ago = $now - (30*60);
my $from = strftime('%y%m%d %T', localtime($ago));
my $to = strftime('%y%m%d %T', localtime($now));

while(<>) {
    print if /$from/../$to/;
}