Cron Expression Checker & Explainer
Validate a five-field cron expression and return it unchanged with an English field explanation. JAN–DEC and SUN–SAT are accepted; no future runs are calculated.
About this cron expression checker & explainer
Validate a five-field cron expression and return it unchanged with an English field explanation. JAN–DEC and SUN–SAT are accepted; no future runs are calculated Transforms and validates developer data structures locally, preventing confidential payload exposure during data wrangling.
Syntax parsing & data transformation logic
Reads a five-field cron expression, validates each minute/hour/day/month/weekday field, then returns the expression with a literal field-by-field English explanation. It does not compute future run times.
Worked conversion & output example
Scenario: Describe a numeric five-field cron mask.
Sample input:
Processing: Validate five bounded numeric fields and render their literal values.
Illustrative output:
Syntax constraints & input size limits
The month field accepts JAN–DEC and the weekday field accepts SUN–SAT case-insensitively, including in lists and ranges. Other fields use numeric syntax. This remains only a five-field syntax checker; it does not calculate future runs or resolve calendar semantics.
Data conversions and formatting in Cron Expression Checker & Explainer reflect standard structured syntax. Verify parsed outputs against your target runtime before deployment.
Local client execution boundary
Data parsing and transformations in Cron Expression Checker & Explainer execute in the local browser tab without remote data transmission.
Data format specifications & language standards
Data interchange formats and language grammar specifications:
- POSIX.1-2017 Base Definitions (crontab specification)
- Vixie Cron Specification
Cron Expression Checker & Explainer verification · Audit standards
How to use it
- Enter a complete five-field cron expression.
- Validate each minute, hour, day, month and weekday field against supported ranges and syntax.
- Read the unchanged expression followed by a field-by-field explanation.
Frequently asked questions
What does Cron Generator return for a valid mask?+
It returns the trimmed five-field expression, a blank line, then `Runs at minute …` and the `Fields:` description. For `*/15 * * * *`, the returned expression remains `*/15 * * * *` and the description identifies minute `*/15`.
Which grammar does Cron Generator actually validate?+
It accepts exactly five fields. The month field accepts JAN–DEC and the weekday field SUN–SAT case-insensitively, including lists and ranges; the other fields use numeric forms, ranges, lists and steps.
Which inputs fail before a cron description is shown?+
It rejects a different field count, values outside the supported numeric ranges, malformed ranges/lists/steps, command text, and unknown month or weekday names. Valid named month and weekday tokens are not rejected merely because they are words.
Does this generator create or execute a schedule?+
No. It only formats the supplied expression locally as browser text; it does not calculate future runs, resolve calendar or timezone semantics, write a crontab, or execute a command.