Trigger Jenkins Job using “Build periodically” and “Poll SCM”

Method 1 – AT CERTAIN TIME AKA Build periodically

Method 2 – AT CERTAIN TIME BUT Build only when there is Code changes AKA Poll SCM

Setting up the cron jobs in Jenkins using “Build periodically” – scheduling the jenins Job

Examples –
To schedule your build every 5 minutes, this will do the job : */5 * * * * OR H/5 * * * *

To the job every 5min past every hour(5th Minute of every Hour) 5 * * * *

To schedule your build every day at 8h00, this will do the job : 0 8 * * *

To schedule your build for 4, 6, 8, and 10 o’clock PM every day – 0 16,18,20,22 * * *

To schedule your build at 6:00PM and 1 AM every day – 0 1,18 * * *

To schedule your build start daily at morning – 03 09 * * 1-5

To schedule your build start daily at lunchtime – 00 12 * * 1-5

To schedule your build start daily in the afternoon – 00 14 * * 1-5

To schedule your build start daily in the late afternoon – 00 16 * * 1-5

To schedule your build start at midnight – 59 23 * * 1-5 OR @midnight

To run a job on 9.30p.m. (at night) on 3rd of May then I ll write or 21.30 on 3/5/2011 – 21 30 3 5 *

Every fifteen minutes (perhaps at :07, :22, :37, :52) 0 – H/15 * * * *

Every ten minutes in the first half of every hour (three times, perhaps at :04, :14, :24) – H(0-29)/10 * * * *

Once every two hours every weekday (perhaps at 10:38 AM, 12:38 PM, 2:38 PM, 4:38 PM) – H 9-16/2 * * 1-5

Once a day on the 1st and 15th of every month except December – H H 1,15 1-11 *

CRON expression

A CRON expression is a string comprising five or six fields separated by white space that represents a set of times, normally as a schedule to execute some routine.

Format

In some uses of the CRON format there is also a seconds field at the beginning of the pattern. In that case, the CRON expression is a string comprising 6 or 7 fields.

Special characters

Support for each special character depends on specific distributions and versions of cron
Asterisk ( * )
The asterisk indicates that the cron expression matches for all values of the field. E.g., using an asterisk in the 4th field (month) indicates every month.
Slash ( / )
Slashes describe increments of ranges. For example 3-59/15 in the 1st field (minutes) indicate the third minute of the hour and every 15 minutes thereafter. The form “*/…” is equivalent to the form “first-last/…”, that is, an increment over the largest possible range of the field.
Comma ( , )
Commas are used to separate items of a list. For example, using “MON,WED,FRI” in the 5th field (day of week) means Mondays, Wednesdays and Fridays.
Hyphen ( – )
Hyphens define ranges. For example, 2000-2010 indicates every year between 2000 and 2010 AD, inclusive.
Percent ( % )
Percent-signs (%) in the command, unless escaped with backslash (\), are changed into newline characters, and all data after the first % are sent to the command as standard input.[7]

Non-Standard Characters

The following are non-standard characters and exist only in some cron implementations, such as Quartz java scheduler.
L – ‘L’ stands for “last”. When used in the day-of-week field, it allows you to specify constructs such as “the last Friday” (“5L”) of a given month. In the day-of-month field, it specifies the last day of the month.
W – The ‘W’ character is allowed for the day-of-month field. This character is used to specify the weekday (Monday-Friday) nearest the given day. As an example, if you were to specify “15W” as the value for the day-of-month field, the meaning is: “the nearest weekday to the 15th of the month.” So, if the 15th is a Saturday, the trigger fires on Friday the 14th. If the 15th is a Sunday, the trigger fires on Monday the 16th. If the 15th is a Tuesday, then it fires on Tuesday the 15th. However if you specify “1W” as the value for day-of-month, and the 1st is a Saturday, the trigger fires on Monday the 3rd, as it does not ‘jump’ over the boundary of a month’s days. The ‘W’ character can be specified only when the day-of-month is a single day, not a range or list of days.
Hash ( # )
‘#’ 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” of a given month.[8]
Question mark ( ? )
In some implementations, used instead of ‘*’ for leaving either day-of-month or day-of-week blank. Other cron implementations substitute “?” with the start-up time of the cron daemon, so that ? ? * * * * would be updated to 25 8 * * * * if cron started-up on 8:25am, and would run at time every day until restarted again.

In addition, @yearly, @annually, @monthly, @weekly, @daily, @midnight, and @hourly are supported as convenient aliases. These use the hash system for automatic balancing. For example, @hourly is the same as H * * * * and could mean at any time during the hour. @midnight actually means some time between 12:00 AM and 2:59 AM.

Reference:
https://en.wikipedia.org/wiki/Cron#CRON_expression

Rajesh Kumar

I’m Rajesh Kumar, a DevOps, SRE, DevSecOps, Cloud, and Platform Engineering expert passionate about sharing practical knowledge, real-world experiences, and industry best practices. I have worked at Cotocus and regularly write about technology, travel, investing, health, product reviews, and digital marketing through my various platforms.

I publish technical articles at DevOps School, travel stories at Holiday Landmark, stock market insights at Stocks Mantra, health and fitness guidance at My Medic Plus, product reviews at TrueReviewNow, and SEO and digital marketing strategies at Wizbrand.