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Edit /etc/crontab and save. then reboot to make the new version take effect (alternatively use kill -HUP <PID> to force an update of the crontab process, where you can find the PID from the ps ux command - see above). There is an example of a crontab:
Logs
The log is kept in /var/log/messages. We believe this is "rotated" (compressed, saved and deleted) automatically by syslog using /etc/logrotate.conf and /etc/syslog.conf, so memory is not eventually exhausted.
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