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37 lines
1.6 KiB
Text
37 lines
1.6 KiB
Text
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anacron (periodic command scheduler)
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anacron is a periodic command scheduler. It executes commands at
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intervals specified in days. Unlike cron, it does not assume that the
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system is running continuously. It can therefore be used to control
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the execution of daily, weekly and monthly jobs (or anything with a
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period of n days), on systems that don't run 24 hours a day. When
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installed and configured properly, Anacron will make sure that the
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commands are run at the specified intervals as closely as
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machine-uptime permits.
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Every time Anacron is run, it reads a configuration file that
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specifies the jobs Anacron controls, and their periods in days. If a
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job wasn't executed in the last n days, where n is the period of that
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job, Anacron executes it. Anacron then records the date in a special
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timestamp file that it keeps for each job, so it can know when to run
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it again. When all the executed commands terminate, Anacron exits.
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It is recommended to run Anacron from the system boot-scripts. For
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example, add the following lines to /etc/rc.d/rc.local:
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if [ -x /usr/sbin/anacron -a -f /etc/anacrontab ]; then
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/usr/sbin/anacron -s > /dev/null 2>&1
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fi
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This way the jobs "whose time has come" will be run shortly after the
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machine boots. A delay can be specified for each job so that the
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machine isn't overloaded at boot time.
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In addition to running Anacron from the boot-scripts, it is also
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recommended to schedule it as a daily cron-job (usually at an early
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morning hour), so that if the machine is kept running for a night,
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jobs for the next day will still be executed.
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See anacron (8), anacrontab (5) and /usr/doc/anacron-2.3/README
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for further information.
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