Cron Every 10 Seconds: Sub-Minute Scheduling Workarounds

Cron's smallest interval is one minute. See the loop-based crontab pattern and systemd timer that actually run a job every 10 seconds.

Cron Expression

* * * * *

Standard cron cannot fire every 10 seconds. This every-minute entry starts a wrapper that loops with sleep, running your job 6 times per minute — details below.

Expression Breakdown

*
Minute
(0-59)
*
Hour
(0-23)
*
Day
(1-31)
*
Month
(1-12)
*
Weekday
(0-6)
Field Value Meaning
Minute * Any minute
Hour * Any hour
Day of Month * Any day
Month * Any month
Day of Week * Any day of the week

There is no cron expression for every 10 seconds — the 5-field cron format bottoms out at one minute. Anything claiming */10 * * * * * works in your crontab is describing a different scheduler (Quartz and some application frameworks accept 6 fields, but Linux crontab does not).

Here’s how to actually get a 10-second cadence.

Workaround 1: Every-Minute Entry + Loop Script

Run a wrapper once a minute that executes your job 6 times, 10 seconds apart:

* * * * * /path/to/every-10s.sh

With every-10s.sh:

#!/bin/bash
# 6 runs per minute: at :00, :10, :20, :30, :40, :50
for i in 0 1 2 3 4 5; do
  /path/to/your/job.sh &
  sleep 10
done

The & backgrounds each run so a slow job doesn’t push later iterations off schedule. If runs must never overlap, drop the & and accept the drift, or use flock.

Workaround 2: systemd Timer

systemd timers handle sub-minute schedules natively:

[Unit]
Description=Run myjob every 10 seconds

[Timer]
OnBootSec=10
OnUnitActiveSec=10
AccuracySec=1s

[Install]
WantedBy=timers.target

AccuracySec=1s matters — systemd’s default accuracy window is 1 minute, which would defeat the point.

When 10-Second Cron Is the Wrong Tool

Ten seconds is polling territory. Before shipping this, ask whether the underlying need is really “react quickly to new data” — if so, a persistent worker process, a message queue consumer, or database change notifications will be more efficient and more precise than 6 process spawns per minute. Cron-plus-sleep is fine for prototypes and low-stakes polling; it’s fragile as core infrastructure.

How to Use

  1. Add the every-minute expression above to your crontab (crontab -e)
  2. Create the loop script and make it executable (chmod +x every-10s.sh)
  3. Add locking with flock if job runs might overlap
  4. Verify the cadence in your job’s own logs, since cron only logs the per-minute launch

Related Cron Examples