How can I create a cron job that will run on the last day of every month?
Question
How can I create a cron job that will run on the last day of every month?
Answer
There is no exact, portable five-field Unix cron expression for “the last day of every month.” Traditional Unix/Vixie cron, robfig/cron, Jenkins built-in cron, and NCrontab do not accept L. 0 0 L * * works with dragonmantank/cron-expression; Quartz and AWS EventBridge support L using their six-field forms. For Unix crontab, use 0 0 28-31 * * with the runtime guard below, so the command continues only when tomorrow is the first day of a month.
crontab
# dragonmantank/cron-expression only; Quartz and AWS need their six-field form00L**
crontab
# portable trigger for a runtime "tomorrow is day 1" guard0028-31**
crontab
# the guarded crontab line (GNU date)# on macOS/BSD use: date -v+1d +\%d0028-31**[ "$(date -d tomorrow +\%d)" = "01" ] && command
Read the guarded trigger field by field: minute 0, hour 0, days 28 through 31, every month, and every day of the week. Your runtime check narrows those four candidate nights to the one true month-end date. The month-enumeration approach you may have seen (0 0 30 4,6,9,11 * for 30-day months and 0 0 31 1,3,5,7,8,10,12 * for 31-day months) is correct for those months, but February breaks it: 28 runs a day early in leap years and 28,29 fires twice in them.
Run 0 0 L * * on CrontapMonths are different lengths, so the last day lands on 28, 29, 30 or 31; a fixed day-of-month cannot follow it.
Why this matters
Month length changes, and February changes again in leap years. Treating February 28 as month-end runs a day early in leap years; listing both 28 and 29 runs twice in those years. Either mistake can close accounting periods, create reports, or rotate data on the wrong date. The candidate-days-plus-runtime-check pattern avoids that month-boundary error on any cron, while L avoids it only when your dialect implements the modifier. The dedicated guides cover Quartz, AWS EventBridge, robfig/cron, Jenkins, NCRONTAB and PHP cron-expression.
See this cron expression on the calendar view example
Related questions
How can I create a cron job that will run on the last day of every month?
Standard cron has no 'last day' value. Use 0 0 L * * where L is supported, or 0 0 28-31 * * plus a check that tomorrow is the 1st. Leap years break month lists.
Can I run a cronjob every three days?
Use 0 0 1-30/3 * * to run at midnight on the 1st, 4th, 7th … 28th. The pattern restarts each month, so month-boundary gaps are 1-4 days, not 72 hours.
How do I set a cron job to run twice a week (bi-weekly)?
Twice a week: 0 0 * * 1,4 runs at midnight on Monday and Thursday. Every other week has no cron syntax: trigger weekly (0 9 * * 1) and gate it in the script.
I am trying to create a Cron expression that runs every day at 8:00 AM and 3:30 PM. I understand how to create an expression that runs once a day, but not at multiple set times.
Use two lines: 0 8 * * * for 08:00 and 30 15 * * * for 15:30. Cron pairs every listed minute with every listed hour, so 0,30 8,15 would run four times.
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I am trying to create a Cron expression that runs every day at 8:00 AM and 3:30 PM. I understand how to create an expression that runs once a day, but not at multiple set times.
WordPress, Shopify, Railway, Cloud Run, Vercel, HubSpot, Ghost, your own box. If it answers HTTP, Crontap can drive it on a clock you can read, in the timezone that actually matters, and page you when something breaks.
