Recurring tasks¶
Scripts that get executed on a regular basis can be implemented using Crontab (source).
Crontab¶
Depending on the distro the crontab configuration is saved in directories like /var/spool/cron/crontabs/.
The crontab configuration file can be edited with crontab -e
To edit the crontab configuration of a specific user run crontab -u <name-of-linux-user> -e
It has the following format:
<minute (0-59)> <hour (0-23)> <day of month (1-31)> <moth of year (1-12)> <day of week (0-6) start with sunday> <command>
Instead of a number for one of these fields an asterisk (*) can be used to allow every possible input for this field.
Time zone¶
Chrontab uses the time zone of your system. Get the current zone with:
timedatectl
Set UTC as time zone:
timedatectl set-timezone UTC
Advanced¶
Fields can have one of these formats:
Description |
Example |
|---|---|
Arbitrary |
|
List |
|
Range |
|
Every nth time |
|
1,5,6
Example:¶
17 3 * * 2 /usr/bin/certbot renew >> /var/log/le-renew.log
Execute on minute 17 of hour 3 every Tuesday.