cronsim 0.1.2

Cron expression parser and evaluator

CronSim

Cron Sim(ulator), a cron expression parser and evaluator.

Experimental and work in progress.

Usage

from datetime import datetime
from cronsim import CronSim

it = CronSim("0 0 * 2 MON#5", datetime.now())
for x in range(0, 10):
    print(next(it))

Outputs:

2044-02-29 00:00:00
2072-02-29 00:00:00
2112-02-29 00:00:00
2140-02-29 00:00:00
2168-02-29 00:00:00
2196-02-29 00:00:00
2208-02-29 00:00:00
2236-02-29 00:00:00
2264-02-29 00:00:00
2292-02-29 00:00:00

Supported Cron Expression Features

CronSim aims to match Debian's cron implementation (which itself is based on Paul Vixie's cron, with modifications). If CronSim evaluates an expression differently from Debian's cron, that's a bug.

CronSim is open to adding support for non-standard syntax features, as long as they don't conflict or interfere with the standard syntax.

Cron Expression Feature Matrix

Feature	Debian	croniter	cronsim
Seconds in the 6th field	No	Yes	Yes
Special character "L"	No	Yes	Yes
N-th weekday of month	Yes	Yes	Yes

Seconds in the 6th field: an optional sixth field specifying seconds. Supports same syntax features as the minutes field.

Example: * * * * * */15 (every 15 seconds).

Special character "L": can be used in the day-of-month field and means "the last day of the month".

Example: 0 0 L * * (at the midnight of the last day of every month).

N-th weekday of month: support for "{weekday}#{nth}" syntax. For example, "MON#1" means "first Monday of the month", "MON#2" means "second Monday of the month".

Example: 0 0 * * MON#1 (at midnight of the first monday of every month).