Cron Expression: Executing a Task Every Second

Cron Expression: Executing a Task Every Second

Cron expression is a popular tool used in scheduling recurring tasks in software development. It provides a simple yet powerful way to define when a task should be executed. In this article, we will explore how to use a Cron expression to execute a task every second.

What is Cron Expression?

A Cron expression is a format consisting of six fields that define the frequency and timing of a task. The six fields represent the second, minute, hour, day of the month, month, and day of the week. Each field can contain a range of values or a specific value. The Cron expression is evaluated as a string and is used by the Cron schedule library in most programming languages.

* * * * * *
# ┬ ┬ ┬ ┬ ┬ ┬
# │ │ │ │ │ └ day of the week (0 - 7) (Sunday to Monday)
# │ │ │ │ └───── month (1 - 12)
# │ │ │ └────────── day of the month (1 - 31)
# │ │ └─────────────── hour (0 - 23)
# │ └──────────────────── minute (0 - 59)
# └───────────────────────── second (0 - 59)

In the example above, the stars represent wildcards, which means the field should accept any value. For instance, * * * * * * means every second, every minute, every hour, every day, every month, and every day of the week. You can also use ranges and lists of values to fine-tune the schedule.

Executing a Task Every Second on Cron Expression

To execute a task every second using Cron expression, you simply need to set the first field (second) to a wildcard (asterisk). The Cron expression * * * * * * will execute the job every second.

import time
from croniter import croniter

def task():
    print("I am a recurring task that runs every second!")

cron = croniter('* * * * * *', time.time())
while True:

In the code above, we use the croniter library to iterate the Cron expression and execute a task every second. We define a task function that prints a message to the console. We create a cron object and start an infinite loop to execute the task every second using the time.sleep(1) function. The time.sleep(1) function ensures that the task is executed once per second.


Cron expression is a powerful tool that can be used to schedule recurring tasks in software development. By setting the first field to a wildcard, you can execute a task every second. The croniter library provides a simple and easy way to iterate the Cron expression and execute a task at the specified schedule. With Cron expression, you can automate repetitive tasks and improve your development efficiency.

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