在linux外解析/评估/生成CrontabExpressions？ [英] Parse/evaluate/generate CrontabExpressions outside of linux?

问题描述

我正在构建一些需要调度输入的软件，我真的想重新使用crontab的设计，因为它只是工作。

I'm building some software that needs a scheduling input, and I'd really like to re-use the design of crontab because it simply works.

a href =http://en.wikipedia.org/wiki/CRON_expression#CRON_expression =nofollow> CrontabExpressions 可以非常简单 * / 5 * * * * 每五分钟运行一次或更复杂 2-59 / 3 1,9,22 11-26 1-6？ 2003 2003年1月11日至26日每月1月至6月每3分钟从上午1点开始，上午9点和晚上10点。

CrontabExpressions can be really simple */5 * * * * "run every five minutes" or more complex 2-59/3 1,9,22 11-26 1-6 ? 2003 "In 2003 on the 11th to 26th of each month in January to June every third minute starting from 2 past 1am, 9am and 10pm".

我不打算使用名为crontab的linux软件，我正在寻找一种方法来正确评估这些表达式（例如，输出匹配的下25个时间戳crontab，或者基于一些抽象的GUI为用户生成它）。

I am not looking to use the linux software called crontab, I'm seeking a way I can evaluate these expressions correctly (for instance, output the next 25 timestamps that match the crontab, or generate it based on some abstracted GUI for the users).

我真的找不到任何库或函数，这在JavaScript或PHP甚至其他语言。如果他们不存在，什么是一个好的方法来做到这一点？我已经知道一个过度复杂的正则表达式可能是错误的答案。我很难在crontab中找到C 源代码

I can't really find any libraries or functions that do this in JavaScript or PHP or even other languages. If they don't exist, what would be a good method to do this? I already know an overly-complicated regular expression is likely to be the wrong answer. I'm having a hard time finding the C source code in crontab that does this task as well, which makes me believe it might not take place here?

推荐答案

要输出下一个25与您可以使用的crontab匹配的时间戳 crontab Python模块：

To output the next 25 timestamps that match the crontab you could use crontab Python module:

from datetime import datetime, timedelta
import crontab

tab = crontab.CronTab('2-59/3 1,9,22 11-26 1-6 ? 2012')

dt = datetime.now()
for _ in xrange(25):
    delay = tab.next(dt) # seconds before this crontab entry can be executed.
    dt += timedelta(seconds=delay)
    print(dt)

输出

Output

2012-01-11 22:41:00
2012-01-11 22:44:00
2012-01-11 22:47:00
2012-01-11 22:50:00
2012-01-11 22:53:00
2012-01-11 22:56:00
2012-01-11 22:59:00
2012-01-12 01:02:00
2012-01-12 01:05:00
2012-01-12 01:08:00
2012-01-12 01:11:00
2012-01-12 01:14:00
2012-01-12 01:17:00
2012-01-12 01:20:00
2012-01-12 01:23:00
2012-01-12 01:26:00
2012-01-12 01:29:00
2012-01-12 01:32:00
2012-01-12 01:35:00
2012-01-12 01:38:00
2012-01-12 01:41:00
2012-01-12 01:44:00
2012-01-12 01:47:00
2012-01-12 01:50:00
2012-01-12 01:53:00

还有 python-crontab 提供 crontab 模块，但具有更丰富的功能（解析/生成）。

There is also python-crontab that provides crontab module but with richer functionality (parse/generate).

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