Regex for Cron expression (5-field)

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About this pattern

Date and time formats vary enormously across regions and systems. The regex here validates structure only — a date like 2024-02-30 would pass format validation but isn't a real date. After regex passes, parse with your language's date library to confirm semantic validity.

Quick usage in different languages

Once you've validated a candidate value matches this pattern, you'll typically use it inside your application code. Each language has its own regex syntax:

• JavaScript: new RegExp(pattern).test(value) or /pattern/.test(value)
• Python: re.match(pattern, value) with raw strings: r"pattern"
• Java: Pattern.compile(pattern).matcher(value).matches()
• C# / .NET: Regex.IsMatch(value, pattern)
• Go: regexp.MustCompile(pattern).MatchString(value) — Go uses RE2 so some advanced features aren't available
• Ruby: value =~ /pattern/ or pattern.match?(value)
• PHP: preg_match('/pattern/', $value)

The explainer's Code tab generates these for any pattern you paste — including the right escaping and idioms for each language.

Common pitfalls

• Anchors matter. The pattern starts with ^ and ends with $ — it expects the entire input to match. To find this pattern inside a longer text, remove the anchors and use the /g flag for multiple matches.
• Case sensitivity. Letter ranges like [A-Z] only match uppercase. Use the i flag or [A-Za-z] for case-insensitive matching.
• Escape user input. If you're building a regex from a string variable, escape regex metacharacters first to avoid bugs or injection — use RegExp.escape-equivalents in your language.
• Performance. For this specific pattern the risk is low, but be cautious of nested quantifiers when adapting it — they can cause exponential backtracking on adversarial input.

See also

Browse all 300 patterns in the library, or open this regex in the interactive explainer to see a token-by-token breakdown, test against custom input, and generate code in seven languages.

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