cron - Crontab timing working not as expected -
i have backup script syncing files every 3rd day.
# m h dom mon dow 0 5 */3 * * backup /home/backup/scripts/system_backup.sh today checking backup , there none.
i expected, because today 27th, 27 / 3 number, execute.
the timestamps of other backups contain days 19, 22, 25
shouldn't execute on days 18, 21, 24, 27 ?
a timestamp of server right fri jun 27 08:52:00 utc 2014.
from man page crontab(5):
step values can used in conjunction ranges. following range ``/'' specifies skips of number's value through range.
basically, means values used @ 0-based indexes divisible <number>.
for dom, * same 1-31. */3 1-31/3. means it'll start @ 1 (index 0) add 3 next 1 (4, @ index 3) , on.
if want cron run on days divisible three, can use 3-31/3 instead.
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