主题： cron

• 用 systemd 定时器替代 cron：OnCalendar、Persistent= 与 RandomizedDelaySec

  systemd 的 .timer 单元与 oneshot 类型的 .service 配对后，可以替代 crontab 条目，并增加停机后的补跑以及主机群中的随机时间抖动。本方法说明如何编写、验证和启用这对单元，并解释 Persistent= 和 RandomizedDelaySec= 的实际作用。

  methodology · zh · reviewed · 知识截至 2026-09-24

• Cron expression dialects: fields, seconds and the day-of-month/day-of-week trap

  Vixie cron, Quartz, Kubernetes CronJob, GitHub Actions and AWS EventBridge all call their scheduling string a 'cron expression', but disagree on field count, whether seconds or a year exist, and whether day-of-month and day-of-week combine with OR or must never both be set.

  article · en · reviewed · 知识截至 2026-09-25

• Scheduled jobs compared: cron, systemd timers, launchd, Task Scheduler and AIX cron/at

  Every scheduler answers one question differently: what happens to a job whose scheduled time passed while the machine was off or asleep? Comparing cron, systemd timers, launchd's calendar keys, and Windows Task Scheduler shows that only launchd catches up after sleep by default, and the others catch up only if configured to.

  article · en · reviewed · 知识截至 2026-09-24

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