Quartz Cron Validator CLI

A command-line tool that validates cron expressions using the Quartz Scheduler's CronExpression.isValidExpression() method.

Features

Validates cron expressions using the industry-standard Quartz library
Returns proper exit codes (0 for valid, 1 for invalid)
Supports both command-line arguments and stdin input
Perfect for use in shell scripts and CI/CD pipelines
Pipe-friendly for Linux/Unix environments
Provides CronValidator.isValidExpression() static method for programmatic use

Building

mvn clean package

This will create cronvalidator.jar in the target/ directory.

Usage

Command Line Argument

java -jar target/cronvalidator.jar "0 0 12 * * ?"
echo $?  # Returns 0 for valid, 1 for invalid

Stdin/Pipe Input

echo "0 0 12 * * ?" | java -jar target/cronvalidator.jar
echo $?  # Returns 0 for valid, 1 for invalid

Shell Script Example

#!/bin/bash
CRON_EXPR="0 0 12 * * ?"

if java -jar cronvalidator.jar "$CRON_EXPR"; then
    echo "Cron expression is valid"
else
    echo "Cron expression is invalid"
fi

Pipeline Example

# Validate multiple cron expressions
cat cron_expressions.txt | while read line; do
    if echo "$line" | java -jar cronvalidator.jar; then
        echo "$line - VALID"
    else
        echo "$line - INVALID"
    fi
done

Programmatic Usage

You can also use the CronValidator.isValidExpression() method directly in your Java code:

import io.github.grokify.cronvalidator.CronValidator;

public class Example {
    public static void main(String[] args) {
        String cronExpr = "0 0 12 * * ?";
        boolean isValid = CronValidator.isValidExpression(cronExpr);
        System.out.println("Expression '" + cronExpr + "' is " + (isValid ? "valid" : "invalid"));
    }
}

Exit Codes

0 - Cron expression is valid
1 - Cron expression is invalid or error occurred

Cron Expression Format

This tool uses Quartz cron expressions, which have 6 or 7 fields:

┌───────────── second (0-59)
│ ┌───────────── minute (0-59)
│ │ ┌───────────── hour (0-23)
│ │ │ ┌───────────── day of month (1-31)
│ │ │ │ ┌───────────── month (1-12)
│ │ │ │ │ ┌───────────── day of week (0-7, 0 and 7 are Sunday)
│ │ │ │ │ │ ┌───────────── year (optional)
│ │ │ │ │ │ │
* * * * * * *

Examples

0 0 12 * * ? - Every day at noon
0 15 10 ? * MON-FRI - 10:15 AM every weekday
0 0/5 14 * * ? - Every 5 minutes starting at 2:00 PM and ending at 2:55 PM, every day
0 0 12 1/5 * ? - 12:00 PM every 5 days every month, starting on the first day of the month

API Documentation

Full Javadoc API documentation is available in the docs/ directory. Open docs/index.html in your web browser to view the complete documentation.

To update the documentation after making code changes:

mvn javadoc:javadoc
rsync -av target/reports/apidocs/ docs/

Dependencies

Java 11+
Quartz Scheduler 2.3.2

grokify/quartz-cron-validator