How to Set Cron Settings
Cron is a job scheduler for Unix-like operating systems, including Linux. Cron allows a user to automate computer tasks by entering commands in cron that call commands, such as a user-written script or a general program, at specific times. Cron is an easy-to-use program, and specific cron settings, such as when to call a function or who has permission to modify a command, are relatively straightforward.
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Instructions
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Open the crontab editor. This allows you to edit the commands that the cron program will read and run. This editor can be opened using the command:
crontab -e
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Decide when you would like your program to run. There are five fields to specify, which are: minute, which is a value from 0 to 59; hour, which is a number from 0 to 23; day of month, which is a number from 1 to 31; month, which is a number from 1 to 12; and day of week, which is a number between 0 and 6, where 0 represents Sunday.
For example, if you would like your program to run at 6:30 am every Monday, as well as the 7th day of every month, the entry would look like:
30 6 7 * 1
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Enter the command you would like to run immediately after the fields. For example, if you would like to run a shell script called "script", located in your home folder, the crontab editor would look like the following:
30 6 7 * 1 bash ~/script
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Tips & Warnings
If you would like cron to call the command at every possible value of the field, use *. For example, in the "hour" field, entering * will call the program at every possible hour, 0 to 23.
To see the cron settings for different users, enter the command "crontab -u user", where "user" is the settings for whom you want to see.
The crontab can be opened in a number of different text editor, including vim, pico and others. Ensure you understand the basic syntax of the editor you are using.
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