systemd timer helper

OnCalendar Builder

Compose a systemd calendar expression, validate the shape, and read what it means in plain language.

Static, local-only parser

OnCalendar=Mon..Fri *-*-* 09:00

OnCalendar expression

Natural language

Valid

Normalized form

Timezone

Syntax Reference

minutely: Every minute.
hourly: Every hour at minute 00.
daily: Every day at midnight.
weekly: Mondays at midnight.
monthly: The first day of each month.
yearly: January 1 each year.
annually: Alias for yearly.

[weekday] [year-month-day] [hour:minute:second] [timezone]

Weekday, date, time, and timezone are each optional. Omitted date means *-*-*; omitted time means 00:00:00; omitted seconds mean :00.

* matches every value.
, separates multiple values.
.. creates ranges such as Mon..Fri or 01..15.
/ adds repetition, as in *:00/15:00 or 1/2.
~ selects days from the end of a month, such as *-02~03.
Seconds may include decimal fractions, rounded by systemd to microseconds.

Input	Use it for	Systemd normalizes to
`minutely`	Every minute.	`--* ::00`
`hourly`	Every hour.	`--* *:00:00`
`daily`	Every day at midnight.	`--* 00:00:00`
`weekly`	Every Monday at midnight.	`Mon --* 00:00:00`
`monthly`	First day of each month.	`--01 00:00:00`
`yearly`	Every January 1.	`*-01-01 00:00:00`
`annually`	Alias for yearly.	`*-01-01 00:00:00`
`quarterly`	First day of each quarter.	`*-01,04,07,10-01 00:00:00`
`semiannually`	January 1 and July 1.	`*-01,07-01 00:00:00`
`Mon..Fri --* 09:00`	Every weekday morning.	`Mon..Fri --* 09:00:00`
`Mon,Wed,Fri --* 06:30`	Three mornings per week.	`Mon,Wed,Fri --* 06:30:00`
`Sat,Sun --* 11:15:00`	Late weekend mornings.	`Sat,Sun --* 11:15:00`
`--* 02:00`	Daily at 2 AM.	`--* 02:00:00`
`--* 00,12:00`	Twice per day.	`--* 00,12:00:00`
`--* 09..17:00`	Hourly during business hours.	`--* 09..17:00:00`
`--* *:00/15:00`	Every 15 minutes.	`--* *:00/15:00`
`*:2/3`	Every three minutes starting at minute 2.	`--* *:02/3:00`
`12..14:10,20,30`	At selected minutes from noon through 2 PM.	`--* 12..14:10,20,30:00`
`03-05 08:05:40`	Every March 5.	`*-03-05 08:05:40`
`--01 00:00`	First day of every month.	`--01 00:00:00`
`--01,15 04:00`	First and fifteenth of every month.	`--01,15 04:00:00`
`*-01,04,07,10-01 00:00`	Quarter starts.	`*-01,04,07,10-01 00:00:00`
`*-02~03 05:00`	Third day before February ends.	`*-02~03 05:00:00`
`2030-01-01 00:00 UTC`	One specific UTC date.	`2030-01-01 00:00:00 UTC`
`weekly Pacific/Auckland`	Weekly in a named timezone.	`Mon --* 00:00:00 Pacific/Auckland`
`Mon --* 08:00 America/New_York`	Monday morning in New York.	`Mon --* 08:00:00 America/New_York`

Reference summarized from systemd.time(7), systemd.timer(5), and the Arch Wiki systemd timers guide.