anacrontab man page
/etc/anacrontab — configuration file for Anacron
The /etc/anacrontab configuration file describes the jobs controlled by anacron(8). It can contain three types of lines: job-description lines, environment assignments, or empty lines.
Job-description lines can have the following format:
period in days delay in minutes job-identifier command
The period in days variable specifies the frequency of execution of a job in days. This variable can be represented by an integer or a macro (@daily, @weekly, @monthly), where @daily denotes the same value as the integer 1, @weekly the same as 7, and @monthly specifies that the job is run once a month, independent on the length of the month.
The delay in minutes variable specifies the number of minutes anacron waits, if necessary, before executing a job. This variable is represented by an integer where 0 means no delay.
The job-identifier variable specifies a unique name of a job which is used in the log files.
The command variable specifies the command to execute. The command can either be a command such as ls /proc >> /tmp/proc or a command to execute a custom script.
Environment assignment lines can have the following format:
Any spaces around VAR are removed. No spaces around VALUE are allowed (unless you want them to be part of the value). The specified assignment takes effect from the next line until the end of the file, or to the next assignment of the same variable.
The START_HOURS_RANGE variable defines an interval (in hours) when scheduled jobs can be run. In case this time interval is missed, for example, due to a power down, then scheduled jobs are not executed that day.
The RANDOM_DELAY variable denotes the maximum number of minutes that will be added to the delay in minutes variable which is specified for each job. A RANDOM_DELAY set to 12 would therefore add, randomly, between 0 and 12 minutes to the delay in minutes for each job in that particular anacrontab. When set to 0, no random delay is added.
Empty lines are either blank lines, line containing white spaces only, or lines with white spaces followed by a '#' followed by an arbitrary comment.
You can continue a line onto the next line by adding a '\' at the end of it.
In case you want to disable Anacron, add a line with 0anacron which is the name of the script running the Anacron into the /etc/cron.hourly/jobs.deny file.
This example shows how to set up an Anacron job similar in functionality to /etc/crontab which starts all regular jobs between 6:00 and 8:00 only. A RANDOM_DELAY which can be 30 minutes at the most is specified. Jobs will run serialized in a queue where each job is started only after the previous one is finished.
# environment variables SHELL=/bin/sh PATH=/sbin:/bin:/usr/sbin:/usr/bin MAILTO=root RANDOM_DELAY=30 # Anacron jobs will start between 6am and 8am. START_HOURS_RANGE=6-8 # delay will be 5 minutes + RANDOM_DELAY for cron.daily 1 5 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
The Anacron README file.
Currently maintained by Pascal Hakim.
For Fedora, maintained by Marcela Mašláňová.