sidsinha has asked for the wisdom of the Perl Monks concerning the following question:

Hi, I have a functionality written in perl but I want to run this function once every specific time of an hour. For example, every hour at x:20 (like 10:20, 11:20, 12:20, 1:20...). I need to build in intelligence in a way that even if i run at 10 AM, it should poll at 10:20 and likewise i trigger the script at 9:30, the next poll interval is still 10:20. Any suggestions? I am doing this in windows. Regards, Sid

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Re: Script to poll every hour
by kennethk (Abbot) on Jul 18, 2013 at 20:44 UTC
    This sounds more like something that should be solved via a cron job, particularly since it sounds like something that should be persistent. The Windows equivalent is using the scheduler, which is found via 
    Start > Programs > Accessories > System Tools > Task Scheduler

    [download]
    or something like that, depending on your version.

    That is, of course, not the question you asked.

    To run a script and then pause it until 20 past the hour, you should use localtime to get the minutes (my $min = (localtime)[1];) and then sleep 60 * the mod of the difference between that and the target (sleep(60 * ((20 - $min) % 60))). If you need better precision, you can include seconds (or even milliseconds) in that calculation.

    #11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

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[d/l]
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      Thankyou Sir, exactly what I wanted!!
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Re: Script to poll every hour
by marinersk (Priest) on Jul 18, 2013 at 23:06 UTC
    Here's a working example of how to get the current time and how to make your Perl script wait a specified amount of time. You should be able to do the rest on your own. :-) 
    #!/usr/bin/perl -w

use strict;

my    %TRUE_FALSE =
(
    '1'    => 'True',
    '0'    => 'False',
);

my    %DAY_OF_WEEK =
(
    '0'    => 'Sunday',
    '1'    => 'Monday',
    '2'    => 'Tuesday',
    '3'    => 'Wednesday',
    '4'    => 'Thursday',
    '5'    => 'Friday',
    '6'    => 'Saturday',
);

{
    &displayTime();
    &waitAwhile(3);
    &displayTime();
}

exit;

sub displayTime
{
    my $nowsse = time;

    my ($nowsec,$nowmin,$nowhou,$nowdom,$nowmon,$nowyea,$nowdow,$nowdo
+y,$nowdst) = localtime($nowsse);
    $nowyea += 1900;
    $nowmon++;

    print "---------------------------------------------\n";
    my $nowDisplay = sprintf "%04d-%02d-%02d\@%02d:%02d:%02d",
        $nowyea, $nowmon, $nowdom, $nowhou, $nowmin, $nowsec
    ;
    print "  Time right now:  $nowDisplay\n";
    print "     Day of Week:  $DAY_OF_WEEK{$nowdow}\n";
    print "     Day of Year:  $nowdoy\n";
    print "Daylight Savings:  $TRUE_FALSE{$nowdst}\n";
    print "---------------------------------------------\n";

}

sub waitAwhile
{
    my ($waitSeconds, @dummy) = @_;
    if (!defined $waitSeconds) { $waitSeconds = 0; }

    if ($waitSeconds <= 0) { $waitSeconds = 3; }

    print "Waiting $waitSeconds seconds\n";
    sleep $waitSeconds;
}


__END__


C:\Steve\Dev\PerlMonks\P-2013-07-18@1650-Time-Computation>perl timeCom
+putation.pl
---------------------------------------------
  Time right now:  2013-07-18@17:03:10
     Day of Week:  Thursday
     Day of Year:  198
Daylight Savings:  True
---------------------------------------------
Waiting 3 seconds
---------------------------------------------
  Time right now:  2013-07-18@17:03:13
     Day of Week:  Thursday
     Day of Year:  198
Daylight Savings:  True
---------------------------------------------

    [download]
    Have fun!
[reply]
[d/l]
      Awesome, I could use this in my script too. THanks a lot
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Re: Script to poll every hour
by hdb (Monsignor) on Jul 18, 2013 at 19:53 UTC

    Calculate the time in seconds until the desired next poll time and put your script to sleep for that many seconds.

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[d/l]
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