Validation

Cron Expression

Validate standard 5-field Unix cron expressions: minute, hour, day-of-month, month, day-of-week.

Available in

JavaScript / ECMAScript code

jsJavaScript

const re = new RegExp("^(\\*|([0-5]?\\d))\\s+(\\*|([01]?\\d|2[0-3]))\\s+(\\*|([1-9]|[12]\\d|3[01]))\\s+(\\*|([1-9]|1[0-2]))\\s+(\\*|[0-7])$", "");
const input = "0 9 * * 1";
const matches = [...input.matchAll(re)];
console.log(matches.map(m => m[0]));

Uses `String.prototype.matchAll` for global iteration (Node 12+ / all modern browsers).

Python (re) code

pyPython

import re

pattern = re.compile(r"^(\*|([0-5]?\d))\s+(\*|([01]?\d|2[0-3]))\s+(\*|([1-9]|[12]\d|3[01]))\s+(\*|([1-9]|1[0-2]))\s+(\*|[0-7])$")
input_text = "0 9 * * 1"
for m in pattern.finditer(input_text):
    print(m.group(0))

Stdlib `re` module — no third-party dependency. Works on Python 3.6+.

Go (RE2) code

goGo

package main

import (
	"fmt"
	"regexp"
)

func main() {
	re := regexp.MustCompile(`^(\*|([0-5]?\d))\s+(\*|([01]?\d|2[0-3]))\s+(\*|([1-9]|[12]\d|3[01]))\s+(\*|([1-9]|1[0-2]))\s+(\*|[0-7])$`)
	input := `0 9 * * 1`
	for _, match := range re.FindAllString(input, -1) {
		fmt.Println(match)
	}
}

Uses `regexp.MustCompile` (panics on bad patterns at startup) and `FindAllString` for all matches.

Pattern

regexengine-agnostic

^(\*|([0-5]?\d))\s+(\*|([01]?\d|2[0-3]))\s+(\*|([1-9]|[12]\d|3[01]))\s+(\*|([1-9]|1[0-2]))\s+(\*|[0-7])$

Raw source: ^(\*|([0-5]?\d))\s+(\*|([01]?\d|2[0-3]))\s+(\*|([1-9]|[12]\d|3[01]))\s+(\*|([1-9]|1[0-2]))\s+(\*|[0-7])$

How it works

Each of the five fields is validated against its allowed range. Minute: 0–59. Hour: 0–23. Day-of-month: 1–31. Month: 1–12. Day-of-week: 0–7 (0 and 7 both mean Sunday). Each field also accepts * for any value.