ANACRONTAB(5)

NAME
/etc/anacrontab - monotonic jobs

DESCRIPTION
The file /etc/anacrontab follows the rules previously set by anacron(8).

Lines starting with ‘#’ are comments.

Environment variables can be set using variable=value alone on a line.

The special RANDOM_DELAY (in minutes) environment variable is translated to RandomizedDelaySec=.

The special START_HOURS_RANGE (in hours) environment variable is translated to the hour component of OnCalendar=. anacron expects a range in the format start-end, but systemd-crontab-generator only uses start.

The other lines are job-descriptions in the white-space-separated format
    period delay job-identifier command
where
period
    is a number of days to wait between each job execution, or one of the special values @reboot, @minutely, @hourly, @midnight, @daily, @weekly, @monthly, @quarterly, @semi-annually, @yearly.
delay
    is the number of extra minutes to wait before starting job, translated to OnBootSec=,
job-identifier
    is a single word used by systemd-crontab-generator to construct dynamic unit names in the form cron-job-identifier-root-0.{timer, service},
command
    is the program to run by the shell.

BUGS
systemd-crontab-generator doesn't support multiline commands.

Any period greater than 30 is rounded to the closest month.

There are subtle differences on how anacron and systemd handle persistent timers: anacron will run a weekly job at most once a week, with a guaranteed minimum delay of 6 days between runs, whereas systemd will try to run it every monday at midnight, or at system boot. In the most extreme case, if a system was booted on sunday, weekly jobs will run that day and the again the next (mon)day.

There is no difference for the daily job.

NOTES
anacron only supports @monthly.

DIAGNOSTICS
After editing /etc/anacrontab, you can run journalctl -n and systemctl list-timers to see if the timers have well been updated.

SEE ALSO
systemd.timer(5), systemd-crontab-generator(8)