What is an example of a matching and non-matching string?

A valid matching string is "*/15 0 1,15 * 1-5". A non-matching string is "invalid cron string".

Is this regex safe from ReDoS (Catastrophic Backtracking)?

Yes, this pattern is optimized for linear execution time and safe for browser-side validation without locking up the UI thread.

HomeRegex Library5-Field Unix Cron Expression Regex

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5-Field Unix Cron Expression Regex

Q: How do I test this regex in JavaScript and TypeScript?

Use regex.test(): const regex = /^(@(annually|yearly|monthly|weekly|daily|hourly|reboot))|(@every (\d+(ns|us|µs|ms|s|m|h))+)|((((\d+,)+\d+|(\d+(\/|-)\d+)|\d+|\*) ?){5,7})$/; const isValid = regex.test(inputString);

Validates standard 5-to-7 field crontab expressions including wildcard, ranges, steps, and shortcuts.

Regular Expression Pattern:

/^(@(annually|yearly|monthly|weekly|daily|hourly|reboot))|(@every (\d+(ns|us|µs|ms|s|m|h))+)|((((\d+,)+\d+|(\d+(\/|-)\d+)|\d+|\*) ?){5,7})$/

Valid Match Example:

*/15 0 1,15 * 1-5

Invalid / Non-Match Example:

invalid cron string

Regex Syntax Breakdown & Explanation

•Matches standard 5 to 7 space-separated fields for minute, hour, day of month, month, and day of week.

Implementation in Popular Languages

JavaScript / TypeScript

const regex = /^(@(annually|yearly|monthly|weekly|daily|hourly|reboot))|(@every (\d+(ns|us|µs|ms|s|m|h))+)|((((\d+,)+\d+|(\d+(\/|-)\d+)|\d+|\*) ?){5,7})$/;
const isValid = regex.test("*/15 0 1,15 * 1-5");
console.log(isValid); // true

Python (re)

import re

pattern = r"^(@(annually|yearly|monthly|weekly|daily|hourly|reboot))|(@every (\d+(ns|us|µs|ms|s|m|h))+)|((((\d+,)+\d+|(\d+(\/|-)\d+)|\d+|\*) ?){5,7})$"
match = re.match(pattern, "*/15 0 1,15 * 1-5")
print(bool(match)) # True

Go (regexp)

package main
import (
  "fmt"
  "regexp"
)

func main() {
  re := regexp.MustCompile(`^(@(annually|yearly|monthly|weekly|daily|hourly|reboot))|(@every (\d+(ns|us|µs|ms|s|m|h))+)|((((\d+,)+\d+|(\d+(\/|-)\d+)|\d+|\*) ?){5,7})$`)
  fmt.Println(re.MatchString("*/15 0 1,15 * 1-5"))
}

Frequently Asked Questions

Everything you need to know regarding specifications, syntax, and security best practices.

The regular expression pattern is /^(@(annually|yearly|monthly|weekly|daily|hourly|reboot))|(@every (\d+(ns|us|µs|ms|s|m|h))+)|((((\d+,)+\d+|(\d+(\/|-)\d+)|\d+|\*) ?){5,7})$/. Validates standard 5-to-7 field crontab expressions including wildcard, ranges, steps, and shortcuts.