A Ruby DSL for outputting Cron intervals.
Using a natural syntax to write cron task intervals assists in generating the correct cron interval you are after instead of trying to remember the cron syntax and conventions.
cron = Cronos::Interval puts cron.new.hourly # => '0 * * * *' puts cron.new.daily # => '0 0 * * *' puts cron.new.weekly # => '0 0 * * 0' puts cron.new.weekdays.at(12.30) # => '30 12 * * 1-5' puts cron.new.weekends.at(12.30) # => '30 12 * * 0,6' puts cron.new.at('1.30pm').daily # => '30 13 * * *' puts cron.new.every(6).hours.on('15th').of(:january) # => '0 0,6,12,18 15 1 *' puts cron.new.every(20).minutes.on('15th'..'18th').of(:jan, :feb, :mar) # => '0,20,40 * 15-18 1,2,3 *' puts cron.new.at(14.45).every(:monday, :tuesday) # => '45 14 * * 1,2'
You can also output the whole cron task string using the schedule method:
puts Cronos.schedule('some_task').every(:Sunday).at('3am') # => '0 3 * * 0 some_task'
This does not actually schedule the task in cron. Cronos is merely a DSL to output the cron intervals.
Certain combinations produce unintuitive results. They should be obvious but just in case I will list some. Such as
Will actually run the task twice weekly
TODO: more weird stuff?
Also cron itself allows days of month and days of week to be set. These are independent of each other.
This will be run on the 15th of January AND every Monday and Tuesday of January, so be aware. Though it is a strange combination anyway, the result is the union of both and not the intersection.
sudo gem install cronos
Adam Meehan (duckpunching.com, firstname.lastname@example.org)
Copyright © 2008 Adam Meehan, released under the MIT license