Jenkins cron — syntax, examples & the H modifier

MIN HOUR DOM MONTH DOW
 H   *   *    *    *

Field      Range
minute     0-59
hour       0-23
day-month  1-31
month      1-12 or JAN-DEC
day-week   0-7 or SUN-SAT (0 and 7 = Sunday)

All standard cron operators (*, ,, -, /) work. Comment lines start with #.

Jenkins-specific. H means “a value chosen by hash of the job name” — deterministic per-job but spread across the range. Common patterns:

• H * * * * — every hour at a stable random minute.
• H/15 * * * * — every 15 minutes, starting at a hash-determined offset.
• H 2 * * * — daily at 02:H (some random minute between 02:00 and 02:59).
• H H * * * — daily at a hash-determined hour and minute.
• H(0-30) * * * * — random minute in the first half of the hour.
• H 0 * * 1-5 — every weekday at midnight (just hash on the minute).

H in the day-of-month or month field is valid but rarely useful — those values change rarely so hashing has limited spreading effect.

pipeline {
  agent any
  triggers {
    cron('H/15 * * * *')
  }
  stages { ... }
}

// Multi-line cron for monthly + nightly:
pipeline {
  agent any
  triggers {
    cron('''
      H 2 * * *           // nightly at 02:H
      H H 1 * *           // monthly on the 1st at hash time
    ''')
  }
}

In the Freestyle job UI, paste your cron lines directly into the “Build periodically” box. Jenkins validates them on save and shows the next firing time in the help text below the field. Comments and TZ prefixes are accepted.

• SCM polling vs. cron — both can fire a build. Use a when block to avoid duplicate runs.
• JVM timezone — defaults to the controller JVM's timezone. Set via TZ prefix or JVM property.
• Concurrency — by default a single job doesn't run concurrently; subsequent triggers queue. Set the build to allow concurrency if you want overlap.
• No L/W/# — use multi-cron or a runtime date check inside the build.