Quartz.net Summary (ii) Crontrigger and cron expressions

Quartz.net's task scheduling, mainly relies on crontrigger and cron expressions. Cron is already in Unix for a long time, it has a strong and reliable scheduling ability. The Crontrigger class is also based on cron scheduling capabilities.

Crontrigger uses cron expressions. It can flexibly set up a variety of planning tasks, such as every Monday to Friday, 8 in the morning to perform a task. However, although Cron expressions are powerful and flexible, they are confusing and difficult to understand. So here's a description of the CRON expression-related configuration. I hope you will help us to understand quickly.

Cron format

Cron expressions are used to configure Crontrigger instances. A cron expression is a string consisting of 6, 7 fields (sub-expressions), and spaces. Each sub-expression describes a separate schedule detail

domain	Force	allowable value	Allow special characters
Seconds	YES	0-59	, - * /
Minutes	YES	0-59	, - * /
Hours	YES	0-23	, - * /
Day of month	YES	1-31	, - * ? /L W
Month	YES	1-12 or Jan-dec	, - * /
Day of week	YES	1-7 or Sun-sat	, - * ? L
Year	NO	Empty, 1970-2099	, - * /

So, like a cron expression string "0 0 10?" * MON ", which means" 12:00 noon every Monday ".

In the list above, it is clear that all the values in the domain have a specific legal scope, and each domain can be configured separately. For example: Day of week (days of the week) must have a value (SUN-SAT) or use special characters, so "0 0 * MON" can be changed to "Mon-fri", "Mon, WED, FRI" even "Mon-wed,sat".

Special Character description

' * ' indicates "each" in the domain. For example, the * in the "Minutes" field indicates every minute.

'? ' in the Day-of-month and Day-of-week fields, indicating "no value specified". This is useful when you need to specify a value for one or two fields without having to set up other domains. For example, I want to be on a day of one months (for example, the tenth), instead of the specific day, I will put "10" in the Day-of-month domain, then "? "In the Day-of-week."

'-' specifies the range, for example, "10-12" in the Hours field, which represents 10 to 12 points.

', ' specifies added value, for example, "Mon,wed,fri" in the Day-of-week field, which means "Monday, Wednesday, and Friday".

'/' does not have a specific value, used to specify the increment of the value, for example, if in the seconds field, ' 0/15 ', it means "starting from 0, every 15 seconds."

' L ' is used only in Day-of-month and Day-of-week, which is a shorthand for "last", but has a different meaning in two domains. For example, the "L" in the Day-of-month field represents the last day of the month, that is, 31st of January, non-leap year February of 28th. If it is used in day-of-week, it means "7" or "SAT". However, this character follows a different value, which means "last week of the month XXX". For example: "6L" or "Fril" represents the last Friday of this month. It can also be used to specify the penultimate day of the last day of the first month, such as "L-3", which indicates the last day of the month. Note: When using the ' L ' option, the most important thing is not to specify a list or range of values, which can cause confusion.

' W ' is used for the most recent day in the Day-of-week domain for a given day (Monday Friday). For example, "15W" means "the most recent working day from month 15th is the week".

' # ' represents the first few weeks of the month. For example: "6#3" or "fri#3" in the Day-of-week field means "third Friday of the month".

Related examples

An expression	Meaning
0 0 12 * *?	12 o'clock noon every day.
0 15 10? * *	Daily 10 o'clock in the morning 15
0 15 10 * *?	Daily 10 o'clock in the morning 15
0 15 10 * *? *	Daily 10 o'clock in the morning 15
0 * 14 * *?	Every day from 2 o'clock in the afternoon to 2 O ' 59 per minute
0 0/5 14 * *?	Every 5 minutes from 2 o'clock in the afternoon to 2 59 every day.
0 0/5 14,18 * *?	Every 55 minutes from 2 o'clock in the afternoon to 2, 59 and 6 to 6 5 every day.
0 0-5 14 * *?	Every day from 2 o'clock in the afternoon to 2 O ' 05 per minute
0 10,44 14? 3 WED	March every Wednesday 2 o'clock in the afternoon 10 and 2 point 44
0 15 10? * Mon-fri	Every Wednesday to Friday 10 o'clock in the morning 15
0 15 10 15 *?	10 o'clock in the morning 15 on the 15th day of every month
0 L *?	10 o'clock in the morning 15 on the last day of each month
0 L-2 *?	The last day of the month, the penultimate day of the next 10 o'clock in the morning 15
0 15 10? * 6L	Last Friday of the month 10 o'clock in the morning 15
0 15 10? * 6L 2002-2005	2002 to 2005 of the last of the monthly Friday 10 o'clock in the morning 15
0 15 10? * 6#3	The third Friday of every month. 10 o'clock in the morning 15
0 0 12 1/5 *?	Starting on the first day of every month, 12 o'clock noon every 5 days
0 11 11 11 11?	Every November 11, 11:11

Note: '? ' and ' * ' influence in Day-of-week and Day-of-month

Reference Link: http://www.quartz-scheduler.net/documentation/quartz-2.x/tutorial/crontrigger.html

Quartz.net Summary (ii) Crontrigger and cron expressions