Cron

Job shedules in Obsidian are specified using cron syntax. This page provides a reference for writing your own cron expressions, and documents the cron extensions that Obsidian supports.

Recurrence

Recurring interval execution (e.g. every 7 minutes, every 3 weeks) cannot always be expressed in a single cron expression. For that reason, Obsidian also supports Recurrence patterns.

Basic Format

Cron expressions are written using 5 fields separated by spaces, as indicated below.

.---------------- minute (0 - 59)
|   .------------- hour (0 - 23)
|   |   .---------- day of month (1 - 31)
|   |   |   .------- month (1 - 12)
|   |   |   |   .----- day of week (0 - 7) (Sunday = 0 or 7)
|   |   |   |   |
*   *   *   *   *

Ordinals indicate specific times, days or months that apply, while an asterisk (*) means there is no restriction on that field. For example, using an asterisk for the month field means the schedule runs during all months, while using "1" would mean it only runs in January. Using 5 asterisks will cause a job to run every minute.

The most basic cron expressions use simple ordinals or an asterisk for each field. As an example, the pattern 30 19 * * 5 means 7:30 PM on all Fridays.

Special Characters and Allowed Values

In addition to ordinals and asterisks, Obsidian supports special characters to support clearer or more complex expressions, as indicated below. These characters allow for ranges, lists and other special handling.

Field Name	Allowed Ordinal Values	Allowed Special Characters
Minute	0-59	* / , -
Hour	0-23	* / , -
Day of Month	1-31	* / , - L W
Month	1-12 or JAN-DEC	* / , -
Day of Week	0-7 or SUN-SAT	* / , - L #

Special Character Usage

Special Character	Examples	Description
Asterisk (*)	0 0 * * * (run every midnight)	Asterisks indicate that the expression will match for all values of the field. For example, using an asterisk in the 4th field (month) would indicate every month.
Forward slash (/)	0/2 * * * * (every even minute)	Forward slashes are used to describe increments. For example, 0/15 or */15 in the 1st field (minutes) would indicate the 0th minute of the hour and every 15 minutes thereafter. The value before the slash indicates the start value, so 1/2 for the 1st field (minutes) would indicate every odd minute.
Comma (,)	0/5,7 * * * * (every 5 minutes, and at 7th minute)	Commas are used to separate items of a list. For example, using "MON,WED,FRI" in the 5th field (day-of-week) would mean Mondays, Wednesdays and Fridays. Commas can also be used to combine ranges and increments.
Hyphen (-)	0-15 * * * * (run from 0th to 15th minute inclusive)	Hyphens are used to define ranges. For example, 1-3 in the 4th field (month) would indicate January through March inclusive. This could also be written as JAN-MAR.
L	0 0 * * 5L (midnight on last Friday of the month)	"L" stands for last, and can be used in the day-of-week or day-of-month fields. For example, "5L" in the day-of-week field would mean the last Friday of a given month. In the day-of-month field, "L" is used alone to specify the last day of the month.
W	0 0 15W * * (midnight on weekday closest to the 15th of the month)	"W" is allowed for the day-of-month field. This is used to specify the weekday nearest the given ordinal. For example,specifying "15W" for the day-of-month field, the meaning is "the nearest weekday to the 15th of the month". If the 15th is a Saturday, the trigger will fire on Friday the 14th. If the 15th is a Sunday, the trigger will fire on Monday the 16th. If the 15th is a Tuesday, then it will fire on Tuesday the 15th. However if you specify "1W" as the value for day-of-month, and the 1st is a Saturday, the trigger will fire on Monday the 3rd, as it will not jump over the boundary of a month's days. The "W" character can only be specified when the day-of-month is a single day, not a range or list of days.
Hash (#)	0 0 * * 5#2 (midnight on 2nd Friday of month)	The hash character is allowed for the day-of-week field, and must be followed by a number between one and five. It allows you to specify constructs such as "the second Friday" (5#2) of a given month.

Shortcut Expressions

Obsidian supports some shorthand expressions to easily input common expressions. These start with the at sign (@).

Shortcut	Long-Form Expression	Description
@yearly	0 0 1 1 *	Run once a year, on Jan 1st at midnight.
@annually	0 0 1 1 *	Same as @annually.
@monthly	0 0 1 * *	Run once a month, on the 1st at midnight.
@weekly	0 0 * * 0	Run once a week, on Sunday at midnight.
@daily	0 0 * * *	Run once a day, at midnight.
@midnight	0 0 * * *	Same as @daily.
@hourly	0 * * * *	Run on the hour, every hour.