Cron Parser
Parse cron expressions.
0분에 실행
필드별 해석
다음 5회 실행 시간
Overview
Convert Cron expressions into human-readable descriptions and calculate the next execution times. Useful for server scheduling, CI/CD pipelines, and batch job configuration.
Formula
Cron expression structure: 5 fields (minute hour day month weekday) or 6 fields (second minute hour day month weekday). Each field uses * (all values), numbers (specific values), , (lists), - (ranges), / (intervals). Parsing algorithm: Parse each field to generate a set of allowed values, then search forward from the current time for the next time that satisfies all field conditions. Example: '0 9 * * 1-5' → weekdays (Mon–Fri) at 9:00 AM.
How to Use
- 1Enter a Cron expression (e.g., */5 * * * *).
- 2A human-readable description is displayed.
- 3View the next N execution times.
- 4Modify individual fields as needed to create the desired schedule.
Tips
- ✔'*/5 * * * *' means every 5 minutes; '0 */2 * * *' means every 2 hours.
- ✔In the weekday field, both 0 and 7 represent Sunday.
- ✔'0 0 1 * *' is midnight on the 1st of every month; '0 0 * * 0' is every Sunday at midnight.
- ✔Use 'crontab -l' to view current cron jobs and 'crontab -e' to edit them.
- ✔Always verify the server timezone. UTC and local time may differ.
FAQ
Q. What does each field in a Cron expression mean?
Standard 5-field format: (1) minute (0–59), (2) hour (0–23), (3) day (1–31), (4) month (1–12), (5) weekday (0–7, where 0 and 7 are Sunday). Some systems also support a seconds field. Each field can use * (all), commas (lists), hyphens (ranges), and slashes (intervals).
Q. What happens when both the day and weekday fields are specified?
In most cron implementations, if both fields are specified, they operate as an OR condition. This means the job runs on the specified date OR the specified weekday. Note that this is not an AND condition.
Q. What are common reasons cron jobs fail to execute?
Common causes include unset environment variables (especially PATH), insufficient script execution permissions, incorrect expression syntax, server timezone differences, and the cron daemon not running. For debugging, redirect stdout and stderr of cron jobs to log files.
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