🔠Want to get alerted when your Cron doesn't run correctly?
Go to Better Stack and start monitoring them in 5 minutes.
Cause of the error
You may encounter this error while creating a new crontab or updating an existing one that has a syntax error.
Solution
Crontabs have simple, but strict syntax rules. Every crontab file has to:
- Start whit a correct cron schedule (can be an environmental variable) or comment on every line
- Contain a username for each cron job
- Contain valid and executable shell expression
- End with a newline
# Example of job definition:
# .---------------- minute (0 - 59)
# | .------------- hour (0 - 23)
# | | .---------- day of month (1 - 31)
# | | | .------- month (1 - 12) OR jan,feb,mar,apr ...
# | | | | .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# | | | | | .---- username
# | | | | | |
# * * * * * user command to be executed
* * * * * root echo 'Hello world!'
Got an article suggestion?
Let us know
Explore more
How to run a cronjob as a specific user?
One of the features of Cron is the ability to run Cron jobs as a specific user. Sometimes you may even want to create a special user with limited privileges just to run Cron jobs. There are two methods how to run cronjob as a specific user.
Questions
How to run cron jobs every 5, 10, or 30 seconds?
By default, cron checks crontabs for cronjobs every minute. If you want to run a job every n seconds you need to use a simple workaround.
Questions
How to view and read cron logs on Ubuntu, Debian and CentOS?
Cron can generate logs, which are very useful in troubleshooting your cron jobs. In this quick tutorial, we will take a look at cron logs – how to find them and how to read them.
Questions
How to prevent duplicate cron jobs from running?
Sometimes you may find that duplicate cronjobs are running at the same time. This may happen when the cronjob takes longer to complete than its execution interval. Here is a simple way to prevent this from happening ever again.
Questions
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
-
How to run a cronjob as a specific user?
One of the features of Cron is the ability to run Cron jobs as a specific user. Sometimes you may even want to create a special user with limited privileges just to run Cron jobs. There are two methods how to run cronjob as a specific user.
Questions -
How to run cron jobs every 5, 10, or 30 seconds?
By default, cron checks crontabs for cronjobs every minute. If you want to run a job every n seconds you need to use a simple workaround.
Questions -
How to view and read cron logs on Ubuntu, Debian and CentOS?
Cron can generate logs, which are very useful in troubleshooting your cron jobs. In this quick tutorial, we will take a look at cron logs – how to find them and how to read them.
Questions -
How to prevent duplicate cron jobs from running?
Sometimes you may find that duplicate cronjobs are running at the same time. This may happen when the cronjob takes longer to complete than its execution interval. Here is a simple way to prevent this from happening ever again.
Questions
Make your mark
Join the writer's program
Are you a developer and love writing and sharing your knowledge with the world? Join our guest writing program and get paid for writing amazing technical guides. We'll get them to the right readers that will appreciate them.
Write for usWriter of the month
Marin Bezhanov
Marin is a software engineer and architect with a broad range of experience working...
Build on top of Better Stack
Write a script, app or project on top of Better Stack and share it with the world. Make a public repository and share it with us at our email.
community@betterstack.comor submit a pull request and help us build better products for everyone.
See the full list of amazing projects on github