Perl parsing through a file based on conditions - regex

Question

I have a very large log file which is updated periodically. It is as follows:
commands: (List of files to be copied)
Exit time: Fri May 10 05:33:00 2013
Exit status: 2
commands: (List of files to be copied)
Exit Time: Fri May 20 05:34:00 2013
Exit status: 2
commands: (List of files to be copied)
Exit Time: Fri May 30 05:50:00 2013
Exit Status: 1
I have following code which creates a hash based on Exit Status
while ($line = <FH>) {
if ($line =~ /Exit time/) {
($exittime, $exittimeval) = split(': ',$line);
$stat{$qbsid} = {
time => $exittimeval
};
}
I now need to create a timestamp based on localtime such that the script does not compare the log file for the time after the timestamp (localtime). I have the code to compare the time as follows
$date1 = "$hr1:$min1:$sec1, $moy1/$dt1/$yr1";
$date2 = "$hr2:$min2:$sec2, $moy2/$dt2/$yr2";
sub to_comparable {
my ($date) = #_;
my ($H,$M,$S,$d,$m,$Y) = $date =~ m{^(\d+):(\d+):(\d+), (\d+)/(\d+)/(\d+)\z}
or die;
return "$Y$m$d$H$M$S";
}
if (to_comparable($date2) > to_comparable($date1)) {
print "right\n";
} else {
print "wrong \n";
}
Here $hr1,$min1,$sec1,$moy1,$dt1 and $yr1 are local time variables while $hr2,$min2,$sec2, $moy2,$dt2 and $yr2 are values obtained from hash.
Preferably while running for the first time it should compare the whole file and a timestamp is created. Afterwards, the above idea starts.
Please correct me if anything is wrong. Thank you.

Answer 1

You might want to consider using Time::Piece, which was first released with perl v5.9.5.
#!/usr/bin/perl
use strict;
use warnings;
use Time::Piece;
{
my $end_date = '2013-05-30';
local $/ = '';
while (<DATA>) {
if (/^Exit Time: (.+)/m) {
my $date = Time::Piece->strptime($1, "%c");
print $date->ymd, "\n" if $date->ymd lt $end_date;
}
}
}
__DATA__
commands: (List of files to be copied)
Exit Time: Fri May 10 05:33:00 2013
Exit status: 2
commands: (List of files to be copied)
Exit Time: Fri May 20 05:34:00 2013
Exit status: 2
commands: (List of files to be copied)
Exit Time: Fri May 30 05:50:00 2013
Exit Status: 1
Output:
2013-05-10
2013-05-20

Answer 2

You'll be forming a 20-digit number (assuming years are 4-digit and the rest are always exactly 2-digit). That's a big number, but it seems fine on my 64-bit UNIX OS; I don't know about yours. Anyway, with a fixed-length string, you could do a string comparison ("ge" instead of ">") if a number that big is an issue.
If any of the inputs (e.g. $moy1) could be a single digit, then your comparison function will not work since the October 1st (2013101) would be before September 30th (2013930). You could require a fixed number of digits using:
my ($H,$M,$S,$d,$m,$Y) = $date =~ m{^(\d\d):(\d\d):(\d\d), (\d\d)/(\d\d)/(\d\d\d\d)\z}
or die;
I'm sure how $qbsid is set (from Exit Status or something else), but since your code isn't complete I assume you have something else to do that.
I'm also not sure how your original time strings (e.g. "Fri May 30 05:50:00 2013") get transformed into the "$hr1:$min1:$sec1, $moy1/$dt1/$yr1" format, but I assume you do that elsewhere as well.