Red Hat Summit4.17. Cron
4.17.1. Vixie cron and Cronie
Red Hat Enterprise Linux 6 includes the cronie package as a replacement for vixie-cron. The main difference between these packages is how the regular jobs (daily, weekly, monthly) are done. Cronie uses the
/etc/anacrontab file, which by default looks like the following:
# the maximal random delay added to the base delay of the jobs RANDOM_DELAY=45 # the jobs will be started during the following hours only START_HOURS_RANGE=3-22 # period in days delay in minutes job-identifier command 1 5 cron.daily nice run-parts /etc/cron.daily 7 25 cron.weekly nice run-parts /etc/cron.weekly @monthly 45 cron.monthly nice run-parts /etc/cron.monthly
These regular jobs will be executed once a day in the 03:00-22:00 time interval, including a random delay. For example, cron.daily will have a 5 minute forced delay plus a random delay of 0-45 minutes. You could also run jobs with no delays, between 4 and 5:
RANDOM_DELAY=0 # or do not use this option at all START_HOURS_RANGE=4-5 # period in days delay in minutes job-identifier command 1 0 cron.daily nice run-parts /etc/cron.daily 7 0 cron.weekly nice run-parts /etc/cron.weekly @monthly 0 cron.monthly nice run-parts /etc/cron.monthly
Features of cronie include:
- Random delay for starting the job in
/etc/anacrontab. - Time range of regular jobs can be defined in
/etc/anacrontab. - Each cron table can have its own defined time zone with the CRON_TZ variable.
- By default, the cron daemon checks for changes in tables with inotify.
For further details about cronie and cronie-anacron, see the Red Hat Enterprise Linux Deployment Guide.
