Cron Expression (Standard 5-Field) Regex for Go

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching cron expression (standard 5-field), ported and verified for Go. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your Go project — whether you're validating in a Gin handler, a gRPC service, or a command-line tool.

Go Implementation

// Cron Expression (Standard 5-Field)
// ReDoS-safe | RegexVault — Dev & Systems > Cron

package validation

import "regexp"

var cronExpressionStandard5fieldRe = regexp.MustCompile(`^(\*|[0-9]|[1-5][0-9])(?:[-/,](?:[0-9]|[1-5][0-9]))? (\*|[01]?[0-9]|2[0-3])(?:[-/,](?:[01]?[0-9]|2[0-3]))? (\*|[1-9]|[12][0-9]|3[01])(?:[-/,](?:[1-9]|[12][0-9]|3[01]))? (\*|[1-9]|1[0-2])(?:[-/,](?:[1-9]|1[0-2]))? (\*|[0-7])(?:[-/,][0-7])?$`)

func ValidateCronExpressionStandard5field(s string) bool {
    return cronExpressionStandard5fieldRe.MatchString(s)
}

// Example
// fmt.Println(ValidateCronExpressionStandard5field("* * * * *")) // true

Test Cases

When to use this pattern

This pattern is drawn from the Dev & Systems > Cron category and carries a ReDoS-safe certification. That matters for Go developers because Go's RE2 engine is inherently safe from catastrophic backtracking, but this pattern has been additionally verified for correctness. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

5 space-separated fields: minute (0-59), hour (0-23), day-of-month (1-31), month (1-12), day-of-week (0-7). Both 0 and 7 are Sunday. Does not catch logically impossible date combinations. Use a dedicated cron library for full semantic validation.