Hello, everyone we are back again and this time with a handy tutorial on how to schedule tasks with Cron jobs
What are Cron jobs?
Cron is utility software used for automating tasks on a server system. “Cron” stands for chronological, jobs which are supposed to run at a particular time. So using a Cron job you could specify to run a script or a command at a specific time on a specific day, week and month.
Syntax to specify a Cron job:
To specify a Cron job, you have to specify the exact time at which you want the command to run. Here is the syntax you need to use to specify a job.
- The number of minutes after the hour (0 – 59)
- The hour in military time (0 – 23)
- The day of the month (1 – 31)
- The month (1 – 12)
- The day of the week (0 – 7)
The Asterisk (*) Symbol:
As can be seen in the image above each asterisk symbol is a field and has a meaning, like the first “asterisk” is for the time in minutes. If you don’t want to specify a value for a field you can leave the Asterisk symbol there (*).
Example: If you want to specify a job that needs to run every month, then leave * in the fourth position that is the month field.
Here are a few examples with description to specify a job:
- 00 16 * * 5 date
The “date” command will run at 4:00 PM in the afternoon every “Friday” of every “Month”
2. 30 16 * 12 5 date
The “date” command will run at 4:30 PM in the afternoon every “Friday” in December
3. 00 16 10 12 * date
The “date” command will run at 4:00 PM in the afternoon on the 10th of December.
4. 00 16 10 12 5 date
The “date” command will run at 4:00 PM in the afternoon if the 10th day was a Friday in December.
With that cleared out, we can move on to the next segment of the article.