A regular expression only works character by character, not token by token. So, if you want to match a two-digit number, you have to specify two characters that can match 0 through 9.

Your expression  [0-59\*] will allow the characters 0,1,2,3,4,5,9 and *, which, likely, isn't what you wanted. To match a digit between 0 and 59, or a *, you could use the following regular expression:

  ([012345]?\d|\*)
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That is, you allow the first digit (if any) to be between 0 and 5, and then require a second digit after it, you just don't care what it is.

For matching digits between 0 and 23, it gets trickier:

  ([01]?\d|2[0123]|\*)
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The approach is to match (optionally) a zero or one, and then any digit. If the first digit is a 2, we explicitly require a 0, 1, 2 or 3.

Is there any reason you're forced to parsing the crontab yourself? There is Schedule::Cron and some other Crontab parsers, and your regular expression does not cover the weirder (Vixie) cron extensions like */3, which allows to trigger an event every 3 units, or 1,5,7,9,11, which would trigger the event at 1 minute, 5 minutes, 7 minutes and so on.

Update: ikegami pointed out that I forgot to allow for *.

Thanks. I realised after I'd posted this that it didn't handle the plethra of other extensions. I'll take a look at the CPAN modules to avoid re-inventing the wheel !

To match a digit between 0 and 59, or a *, you could use the following regular expression:

  ([012345]?\d)
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Actually, that would fail on single digit entries between 0 and 5 - because the first (optional) part of the expression would match, and then there would be no 2nd digit to match the second (required) part (\d). For the sake of the exercise, I had a play around with it and the following seems to work (for 0-59):

/^(?:[0-9*]|[12345]\d)$/
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(But I also echo your sentiments about not re-inventing the wheel)

Cheers,
Darren :)

This is a quick, nasty way of matching a range without spending a lot of effort on crafting a clever regular expression.

@range = (0 .. 59);
{
    local $" = '|';
    $rxMatchIt = qr{(@range)};
}
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You end up with a regular expression which says match 0 or 1 or ... 59. This falls over if there are leading zeros but could easily be adapted to cope. I like nifty regular expressions but sometimes quick and dirty gets the job done.

Cheers,

JohnGG

On Perl 5.8.5, the pattern works for me:

#!perl -w

for (qw(
  00 01 02 03 04 05 06 07 08 09
   0  1  2  3  4  5  6  7  8  9
  10 20 30 40 50 58 59
)) {
    die "Ooops: $_ didn't match the regular expression"
        unless /([012345]?\d)/;
};

print "All numbers passed.";
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You're not using a regex range properly. It should be:

$newtime !~ /((\d{1,2}|\*)\s+){5,}/
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This looks for one or two digits OR an asterisk followed by whitespace and looks for 5 of those groups.

$newtime !~ m#^((\d{1,2}(-\d{1,2})?|\*)(/\d{1,2})?\s?){5}$#
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In perl6.....

#!/usr/bin/pugs
use v6;

rule minute {  <[1..5]>?\d   | <[*]> };
rule hour   {  <[1..2]>?\d   | <[*]>  };
rule day    {  31 | 30       | <[1..2]>?\d   |   <[*]>   }
rule month  {  1?\d          | <[*]>  }
rule day_of_week { <[0..6]>  | <[*]> }

rule crontab { <minute> \s+ <hour> \s+ <day> \s+ <month> \s+ <day_of_w
+eek> }


my $crontab = "0 10 * * *" ~~ /<crontab>/;
my $match = $crontab<crontab>;
say "Minute: $match<minute>\nHour:   $match<hour>\n"
  ~ "Day:    $match<day>\nMonth:  $match<month>\n"
  ~ "Day of Week: $match<day_of_week>";
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1;0 eric256@feather:~/tests$ pugs crontab.p6
Minute: 0
Hour:   10
Day:    *
Month:  *
Day of Week: *
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rule hour { [1\d | 2<[0..4]>] | 0?\d | <[*]> } rather, assuming that the range for hours is 1..24 and not 0..23.

similarly,

rule day { 31 | 30 | <[0..2]>?\d | <[*]> }
rule month { 1<[210]> | 0?\d | <[*]> }
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As well as

23 0-23/2 * * * command
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which runs 'command' 23 minutes after midn, 2am, 4am ..., everyday.

Cheers, Flo

And many cron daemons also allow special values such as @reboot - as I wrote about today elsewhere.

Steve
--

#!/usr/bin/perl

use strict;
use warnings;

use DateTime::Event::Cron;

my @crontab = ( '*/3 15 1-10 3,4,5 */2',
                '* * * * 1-4,5-7,11,20',
                '* * * 1-4,5-7,11,20 *',
                '* * 1-4,5-7,11,20 * *',
                '* 1-4,5-7,11,20 * * *',
                '1-4,5-7,11,20 * * * *',
              );

my $set;

foreach my $line (@crontab) {
    eval {
       $set = DateTime::Event::Cron->from_cron( $line );
    };
    print "$line: ", ($@ ? $@ : 'OK'), "\n";
}
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*/3 15 1-10 3,4,5 */2: OK
* * * * 1-4,5-7,11,20: Field value (20) out of range (1-7)
* * * 1-4,5-7,11,20 *: Field value (20) out of range (1-12)
* * 1-4,5-7,11,20 * *: OK
* 1-4,5-7,11,20 * * *: OK
1-4,5-7,11,20 * * * *: OK
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