Jenkins Cron H (Hash) Symbol
Jenkins uses standard cron fields plus a special H symbol. H means 'hash' — Jenkins picks a stable but job-specific value in the allowed range, so jobs spread their load instead of all firing exactly at minute 0.
What H does
H * * * * runs once an hour at a minute Jenkins chooses from the job name hash — stable per job, but different across jobs. This avoids the thundering herd of everything running at 0 * * * *.
H with ranges and steps
H/15 * * * * runs every 15 minutes at a hashed offset (e.g. 7,22,37,52). H H(0-7) * * * runs once daily at a random minute between midnight and 7 AM. H H * * 1-5 is a once-a-day weekday build.
Where to set it
Job → Build Triggers → Build periodically, or triggers { cron('H/15 * * * *') } in a Jenkinsfile.
Why not just use a fixed minute?
Hard-coding 0 makes many jobs collide at the top of the hour. H keeps each job's time consistent while distributing load across the controller.
FAQ
What does H mean in a Jenkins cron expression?
H is 'hash' — Jenkins picks a stable value from the job name within the field's range, so jobs spread out instead of all firing at minute 0.
What is H/15 in Jenkins cron?
Run every 15 minutes, but at a hashed starting offset (like 7,22,37,52) rather than 0,15,30,45, to distribute load.
How do I run a Jenkins job once a day at a random time?
Use H H * * * (any minute, any hour) or H H(0-7) * * * to pin it to a random time within a window such as midnight to 7 AM.