#cron #crontab #parser

cron-parser

Library for parsing cron expressions with timezone support

20 releases

0.7.9 Feb 6, 2021
0.7.7 Oct 28, 2020
0.7.6 Jul 6, 2020
0.7.4 Mar 17, 2020
0.7.0 Nov 19, 2019

#105 in Parser implementations

Download history 33/week @ 2021-09-29 38/week @ 2021-10-06 96/week @ 2021-10-13 56/week @ 2021-10-20 74/week @ 2021-10-27 95/week @ 2021-11-03 65/week @ 2021-11-10 71/week @ 2021-11-17 73/week @ 2021-11-24 145/week @ 2021-12-01 83/week @ 2021-12-08 38/week @ 2021-12-15 14/week @ 2021-12-22 16/week @ 2021-12-29 42/week @ 2022-01-05 45/week @ 2022-01-12

118 downloads per month
Used in 4 crates (3 directly)

BSD-3-Clause

15KB
171 lines

cron parser

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Library for parsing cron expressions with timezone support.

Example:

use chrono::{TimeZone, Utc};
use chrono_tz::Europe::Lisbon;
use cron_parser::parse;

fn main() {
   if let Ok(next) = parse("*/5 * * * *", &Utc::now()) {
        println!("when: {}", next);
   }

   // passing a custom timestamp
   if let Ok(next) = parse("0 0 29 2 *", &Utc.timestamp(1893456000, 0)) {
        println!("next leap year: {}", next);
        assert_eq!(next.timestamp(), 1961625600);
   }

   assert!(parse("2-3,9,*/15,1-8,11,9,4,5 * * * *", &Utc::now()).is_ok());
   assert!(parse("* * * * */Fri", &Utc::now()).is_err());

   // use custom timezone
   assert!(parse("*/5 * * * *", &Utc::now().with_timezone(&Lisbon)).is_ok());
}

Cron table:

# ┌─────────────────────  minute (0 - 59)
# │ ┌───────────────────  hour   (0 - 23)
# │ │ ┌─────────────────  dom    (1 - 31) day of month
# │ │ │ ┌───────────────  month  (1 - 12)
# │ │ │ │ ┌─────────────  dow    (0 - 6 or Sun - Sat)  day of week (Sunday to Saturday)
# │ │ │ │ │
# │ │ │ │ │
# │ │ │ │ │
# * * * * * <command to execute>
Field Required Allowed values Allowed special characters
Minutes Yes 0–59 * , - /
Hours Yes 0–23 * , - /
Day of month Yes 1–31 * , - /
Month Yes 1–12 * , - /
Day of week Yes 0–6 or Sun-Sat * , - /

For the day of the week, when using a Weekday (Sun-Sat) the expression */Day is not supported instead use the integer, reasons for this is that for example */Wed = */3 translates to run every 3rd day of week, this means Sunday, Wednesday, Saturday.

  • * any value
  • , value list separator
  • - range of values
  • / step values

Depends on crate chrono.

Example of Cargo.toml:

[dependencies]
chrono = "^0.4"
cron-parser = "*"

Getting the next 10 leap year iterations:

use chrono::{DateTime, Utc};
use cron_parser::parse;

fn main() {
    let now = Utc::now();
    let mut crons = Vec::<DateTime<Utc>>::new();
    let mut next = parse("0 0 29 2 *", &now).unwrap();
    for _ in 0..10 {
        next = parse("0 0 29 2 *", &next).unwrap();
        crons.push(next);
    }
    for x in crons {
        println!("{} - {}", x, x.timestamp());
    }
}

It will print something like:

2024-02-29 00:00:00 UTC - 1709164800
2028-02-29 00:00:00 UTC - 1835395200
2032-02-29 00:00:00 UTC - 1961625600
2036-02-29 00:00:00 UTC - 2087856000
2040-02-29 00:00:00 UTC - 2214086400
2044-02-29 00:00:00 UTC - 2340316800
2048-02-29 00:00:00 UTC - 2466547200
2052-02-29 00:00:00 UTC - 2592777600
2056-02-29 00:00:00 UTC - 2719008000
2060-02-29 00:00:00 UTC - 2845238400

Dependencies

~1MB
~12K SLoC