I would suggest calculating the time to be compared against once at the beginning of the script, and directly compare that with the date/time you extract from the file you are reading. The same type problem was discussed here.

One advantage you have in your file is that the format for the date/time sorts naturally because the most significant parts of the date begin at the left going to the right.

That is 'YYYY/MM/DD HH:MM:SS' is in a good order for sorts or comparisons. 

#!/usr/dist/share/perl,v5.003/5bin.sun4/perl
use strict;
use warnings;
use Time::Local qw/ timelocal_nocheck /;;
use POSIX qw/ strftime /;

my $secs = 3600; # 1 hour

my ($s, $m, $h, $d, $mon, $y) = localtime;

my $time_ago = strftime "%Y/%m/%d %H:%M:%S",
    localtime timelocal_nocheck $s - $secs, $m, $h, $d, $mon, $y;

print "$time_ago was one hour ago\n";

my $mailprog = "|/usr/sbin/sendmail -t";      
my $lst_email = 'someone@outthere.com';             
  
# DATA should be saved as the spaecial filehandle
# for self-contained programs (like this one)                         
+             
#open (my $in, "/mylist.log") || die ("Can't Open data File: $!\n"); 

# while (<$in>) {
while (<DATA>) {
    chomp;
    my ($datestamp, $status, $location) = split /\|/;
    if ($datestamp lt $time_ago && $status eq 'red') {
        # do email notification
        print "red for more than an hour\n$_\n";
    }
}

__DATA__
2011/04/12 12:50:24|red|florida
2011/04/12 15:20:21|green|tampa
2011/04/12 15:30:12|red|miami

[download]
Update: I hour ago could have been written:

my $hrs = 1;

and then subtracted from $h in the $time_ago formation.

my $time_ago = strftime "%Y/%m/%d %H:%M:%S",
    localtime timelocal_nocheck $s, $m, $h - $hrs, $d, $mon, $y;

[download]
To avoid possible errors in the time calculation, you could use a module made for dealing with dates, like DateTime.

use DateTime;

my $date = DateTime->now->subtract(hours => 1);
my $hr_before = $date->set_time_zone('local')->strftime("%Y/%m/%d %H:%
+M:%S");

[download]

In reply to Re: Compare field andsend mail by Cristoforo
in thread Compare field andsend mail by britney

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