Cron Expression for Every Minute
The cron expression for every minute is * * * * * — five asterisks, one for each field. It's the most often standard cron can run anything: once at the start of every minute, 60 times an hour and 1,440 times a day.
Every minute.
* * * * *Standard 5-field crontab syntax. Day of month and day of week are OR'd when both are set.
What it does
Each * means “every value this field allows”, so the expression matches every minute of every hour, on every day of every month. The cron daemon wakes up once a minute to check its schedules, which is also why a minute is the limit: there's no finer unit to match against. */1 * * * * is an equivalent, longer way to write the same thing.
Minute-level jobs suit work that has to react quickly but can't run as a long-lived process: draining a small queue of outgoing emails, pushing metrics to a monitoring service, checking whether a deploy has finished, or sending a heartbeat so an uptime monitor notices when a machine stops responding. For anything that must react within seconds, a service that listens for events is the better tool.
At 1,440 runs a day, small costs add up. Each run starts a fresh process, loads configuration and opens connections, and if a run ever takes longer than a minute, the next one starts on top of it. Guard the command with flock -n /tmp/job.lock so an overlapping run exits straight away, and send its output to a log file rather than to cron's mail, or the mailbox fills up by lunchtime.
How * * * * * works, field by field
| FIELD | VALUE | MEANING |
|---|---|---|
| Minute | * | every minute |
| Hour | * | every hour |
| Day of month | * | every day of the month |
| Month | * | every month |
| Day of week | * | every day of the week |
Put together, cron reads * * * * * as: “Every minute.”
To see further ahead, paste the expression into the cron calculator, which lists the next ten run times and counts how many times the schedule runs in a year.
Frequently asked questions
Does * * * * * run at the start of each minute?
Yes. Cron checks its schedules at the top of every minute and starts matching jobs then, usually within the first second or two. Standard cron has no way to pick a different second.
Is */1 * * * * the same as * * * * *?
Yes. A step of 1 over the whole range selects every value, so both run every minute. The plain * form is shorter and far more common.
Can GitHub Actions run a workflow every minute?
No. GitHub Actions runs scheduled workflows at most once every 5 minutes, so * * * * * won't run every minute there. System crontab and Kubernetes CronJobs do run it every minute.