Cron Parser

When this schedule fires

Pick Linux Crontab (5 fields), Spring @Scheduled (6 fields, seconds first) or Quartz (6 fields, or 7 with a year). The page explains each field and lists the next 10 runs on this computer’s clock. It does not install the job. To build one from a time of day or from @daily, use the crontab generator. Timestamps are Unix timestamp.

How to use it

1. Format is Linux Crontab (5), Spring @Scheduled (6) or Quartz (6–7). The line under the menu states the field order and which number is Sunday.
2. Type the expression, open Preset, or edit each row under Fields. Preset lists Every minute, Every hour, Every day at midnight, Every Sunday at midnight, Every 15 minutes on weekdays, 09–17, and First day of the month at midnight. The buttons under the box load that list for the current format, and also Daily at 02:00, Weekends at 09:00, Minutes 5/15, Every 2 hours at minute 30, and 1 January. Spring and Quartz also list Last day of the month at 23:00, the weekday nearest the 15th, the first Monday at 10:15, and the last Friday at 10:15. Quartz also lists 1 January 2030. The link beside the buttons opens the crontab generator. Each row has Every, Range, Step and Specific. Specific shows the values: seconds and minutes 0–59, hours 0–23, days 1–31, months 1–12, weekdays SUN–SAT. Spring and Quartz also offer Not set (?), Last day (L), Last weekday (LW), Nearest weekday (W), Nth weekday (#) and Last weekday (nL). A change under Fields rewrites the expression. A field the rows cannot show stays on Custom and keeps the text.
3. Update as you type is on. Explain runs once. Show Example loads the weekday sample for the current format: Linux */15 9-17 * * 1-5, Spring 0 */15 9-17 * * MON-FRI, Quartz 0 */15 9-17 ? * MON-FRI.
4. The result names each field, then Next 10 runs. Clear All empties the expression and the result and sets every field back to Every. Copy Result copies that text. Switching format adds or drops the seconds field, turns ? into * on Linux, and rewrites weekday numbers as SUN–SAT so the same days stay selected.

Which dates match

Linux is minute, hour, day of month, month, day of week. Sunday is 0, 7 or SUN. Monday is 1. There is no ?, L, W or #. If both the day of month and the day of week are restricted, either match is enough, and the result says so.

Spring adds seconds in front. Sunday uses the same numbers as Linux. ? means that field is ignored. L is the last day of the month. 15W is the weekday nearest the 15th and stays inside the month. LW is the last weekday. MON#1 is the first Monday. 6L is the last Saturday, because 6 is Saturday.

Quartz uses the same six fields, plus an optional year such as 2024-2030. Sunday is 1 or SUN. Monday is 2. Saturday is 7. 6L is the last Friday. One of the day or the weekday should be ?, as in 0 0 2 * * ? for 02:00 every day. If both are specific, the result still lists a run when either field matches, and it warns. Names SUN–SAT and JAN–DEC work in any letter case and mean the same day or month in all three formats.

A hyphen is a range, a comma is a list, and a slash is a step. */15 steps from the start of the field. 5/15 starts at 5 and steps to the end, so minutes are 5, 20, 35 and 50. Times are local, not UTC. With a seconds field the list steps by seconds; otherwise it steps by minutes.

Where people use it

• Checking a crontab line such as 0 2 * * * before it is installed.
• Writing Spring 0 0 2 * * * for 02:00 every day.
• Checking Quartz 0 15 10 ? * 6L (last Friday at 10:15) or 0 0 23 L * ? (23:00 on the last day of the month).

Questions