Anacron

Since personal computers, unlike servers, are not running 24 hours a day, the daily user data backups should be started by anacron instead of the usual cron.

Anacron will run the backup job once a day, whenever the computer is turned on and not running on battery.

Unlike cron, anacron is normally used for system administrative jobs only and does not run individual user jobs. This document describes how to setup anacron for individual users, so they can run their personal periodic jobs.

Directory Structure

Create anacron directories in the users home directory:

$ mkdir -p ~/.anacron/cron.{daily,weekly,monthly} ~/.anacron/spool

This creates the following directory structure:

  • ~/.anacron/cron.daily

  • ~/.anacron/cron.monthly

  • ~/.anacron/cron.weekly

  • ~/.anacron/spool

The anacrontab File

Anacron reads the list of jobs from the configuration file anacrontab

Create and edit the file ~/.anacron/anacrontab and replace username and home directory with your own literal values (shell variables won’t work here):

# See anacron(8) and anacrontab(5) for details.
MAILTO=user@example.net
SHELL=/bin/bash
LOGNAME=${USER}
PATH=/home/user/bin:/home/user/.local/bin:/usr/local/bin:/bin:/usr/bin

# period  delay  job-id       command
1          5     daily-cron   nice run-parts --report /home/user/.anacron/cron.daily
7         10     weekly-cron  nice run-parts --report /home/user/.anacron/cron.weekly
@monthly  15     monthly-cron nice run-parts --report /home/user/.anacron/cron.monthly

Run on Login

To run anacron on every login edit the file ~/.profile and add the following line at the bottom:

...
/usr/sbin/anacron -t /home/user/.anacron/anacrontab -S /home/user/.anacron/spool

Run every Hour

To make anacron check every hour, if there is anything to do, edit the users crontab file as follows:

$ crontab -e

This opens an editor, where the following lines need to be added at the bottom:

...
MAILTO=user@example.net
...
# Run anacron every hour to check for daily/monthly/weekly jobs to run
@hourly /usr/sbin/anacron -t /home/user/.anacron/anacrontab -S /home/user/.anacron/spool
#

Also replace username and home directory with your own literal values (shell variables won’t work here)