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(8) expects a range in the format start-end, but systemd-crontab-generator(8) 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-generatorto construct dynamic unit names in the form cron-anacron-job-identifier-MD5.{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
Real anacron only accepts @monthly and @yearly as period; all others listed above are systemd.cron(7)'s extensions.
Unlike crontab(5), every anacrontab(5) job is persistent by default.
DIAGNOSTICS
After editing /etc/anacrontab, you can run
journalctl -n and
systemctl list-timers to see
if the timers have well been updated.