1Schedule::Cron::Events(U3s)er Contributed Perl DocumentatSicohnedule::Cron::Events(3)
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NAME

6       Schedule::Cron::Events - take a line from a crontab and find out when
7       events will occur
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SYNOPSIS

10               use Schedule::Cron::Events;
11               my @mon = qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec);
12
13               # a crontab line which triggers an event every 5 minutes
14               # initialize the counter with the current time
15               my $cron1 = new Schedule::Cron::Events( '*/5 * * * * /bin/foo', Seconds => time() );
16
17               # or initialize it with a date, for example 09:51:13 on 21st June, 2002
18               my $cron2 = new Schedule::Cron::Events( '*/5 * * * * /bin/foo', Date => [ 13, 51, 9, 21, 5, 102 ] );
19
20               # you could say this too, to use the current time:
21               my $cron = new Schedule::Cron::Events( '*/5 * * * * /bin/foo',  Date => [ ( localtime(time()) )[0..5] ] );
22
23               # find the next execution time
24               my ($sec, $min, $hour, $day, $month, $year) = $cron->nextEvent;
25               printf("Event will start next at %2d:%02d:%02d on %d %s, %d\n", $hour, $min, $sec, $day, $mon[$month], ($year+1900));
26
27               # find the following occurrence of the job
28               ($sec, $min, $hour, $day, $month, $year) = $cron->nextEvent;
29               printf("Following event will start at %2d:%02d:%02d on %d %s, %d\n", $hour, $min, $sec, $day, $mon[$month], ($year+1900));
30
31               # reset the counter back to the original date given to new()
32               $cron->resetCounter;
33
34               # find out when the job would have last run
35               ($sec, $min, $hour, $day, $month, $year) = $cron->previousEvent;
36               printf("Last event started at %2d:%02d:%02d on %d %s, %d\n", $hour, $min, $sec, $day, $mon[$month], ($year+1900));
37
38               # see when the job would have next run at a point in time
39               $cron->setCounterToDate(0, 18, 1, 26, 9, 85);   # that's 26th October, 1985
40               ($sec, $min, $hour, $day, $month, $year) = $cron->nextEvent;
41               printf("Event did start at %2d:%02d:%02d on %d %s, %d\n", $hour, $min, $sec, $day, $mon[$month], ($year+1900));
42
43               # turn a local date into a Unix time
44               use Time::Local;
45               my $epochSecs = timelocal($sec, $min, $hour, $day, $month, $year);
46               print "...or that can be expressed as " . $epochSecs . " seconds which is " . localtime($epochSecs) . "\n";
47
48       Here is a sample of the output produced by that code:
49
50               Event will start next at  0:45:00 on 28 Aug, 2002
51               Following event will start at  0:50:00 on 28 Aug, 2002
52               Last event started at  0:40:00 on 28 Aug, 2002
53               Event did start at  1:20:00 on 26 Oct, 1985
54               ...or that can be expressed as 499134000 seconds which is Sat Oct 26 01:20:00 1985
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56       Note that results will vary according to your local time and timezone.
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DESCRIPTION

59       Given a line from a crontab, tells you the time at which cron will next
60       run the line, or when the last event occurred, relative to any date you
61       choose. The object keeps that reference date internally, and updates it
62       when you call nextEvent() or previousEvent() - such that successive
63       calls will give you a sequence of events going forward, or backwards,
64       in time.
65
66       Use setCounterToNow() to reset this reference time to the current date
67       on your system, or use setCounterToDate() to set the reference to any
68       arbitrary time, or resetCounter() to take the object back to the date
69       you constructed it with.
70
71       This module uses Set::Crontab to understand the date specification, so
72       we should be able to handle all forms of cron entries.
73

METHODS

75       In the following, DATE_LIST is a list of 6 values suitable for passing
76       to Time::Local::timelocal() which are the same as the first 6 values
77       returned by the builtin localtime(), namely these 6 numbers in this
78       order
79
80       ·   seconds
81
82           a number 0 .. 59
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84       ·   minutes
85
86           a number 0 .. 59
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88       ·   hours
89
90           a number 0 .. 23
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92       ·   dayOfMonth
93
94           a number 0 .. 31
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96       ·   month
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98           a number 0 .. 11 - January is *0*, December is *11*
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100       ·   year
101
102           the desired year number *minus 1900*
103
104       new( CRONTAB_ENTRY, Seconds => REFERENCE_TIME, Date => [ DATE_LIST ] )
105           Returns a new object for the specified line from the crontab. The
106           first 5 fields of the line are actually parsed by Set::Crontab,
107           which should be able to handle the original crontab(5) ranges
108           aswell as Vixie cron ranges and the like. It's up to you to supply
109           a valid line - if you supply a comment line, an environment
110           variable setting line, or a line which does not seem to begin with
111           5 fields (e.g. a blank line), this method returns undef.
112
113           Give either the Seconds option or the Date option, not both.
114           Supply a six-element array (as described above) to specify the date
115           at which you want to start.  Alternatively, the reference time is
116           the number of seconds since the epoch for the time you want to
117           start looking from.
118
119           If neither of the 'Seconds' and 'Date' options are given we use the
120           current time().
121
122       resetCounter()
123           Resets the object to the state when created (specifically resetting
124           the internal counter to the initial date provided)
125
126       nextEvent()
127           Returns a DATE_LIST for the next event following the current
128           reference time.  Updates the reference time to the time of the
129           event.
130
131       previousEvent()
132           Returns a DATE_LIST for the last event preceding the current
133           reference time.  Updates the reference time to the time of the
134           event.
135
136       setCounterToNow()
137           Sets the reference time to the current time.
138
139       setCounterToDate( DATE_LIST )
140           Sets the reference time to the time given, specified in seconds
141           since the epoch.
142
143       commandLine()
144           Returns the string that is the command to be executed as specified
145           in the crontab - i.e. without the leading date specification.
146

ERROR HANDLING

148       If something goes wrong the general approach is to raise a fatal error
149       with confess() so use eval {} to trap these errors. If you supply a
150       comment line to the constructor then you'll simply get back undef, not
151       a fatal error. If you supply a line like 'foo bar */15 baz qux
152       /bin/false' you'll get a confess().
153

DEPENDENCIES

155       Set::Crontab, Time::Local, Carp. Date::Manip is no longer required
156       thanks to B Paulsen.
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159       Copyright 2002 P Kent
160
161       This library is free software; you can redistribute it and/or modify it
162       under the same terms as Perl itself.
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166perl v5.12.0                      2003-03-05         Schedule::Cron::Events(3)
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