196 lines
3.6 KiB
HTML
196 lines
3.6 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML
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>Dealing with Down Times (Cron Jobs)</TITLE
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TITLE="Linux on the Road"
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>Chapter 15. Different Environments</TD
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NAME="mobile-guide-p5c1s7-dealing-with-down-times"
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>15.9. Dealing with Down Times (Cron Jobs)</H1
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><P
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> A cron-like program that doesn't go by time: <B
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CLASS="command"
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>anacron</B
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>
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(like "anac(h)ronistic") is a periodic command scheduler. It executes
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commands at intervals specified in days. Unlike <B
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CLASS="command"
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>cron</B
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>,
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it does not assume that the system is running continuously. It can
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therefore be used to control the execution of daily, weekly and monthly
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jobs (or anything with a period of n days), on systems that don't run 24
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hours a day. When installed and configured properly,
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<B
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CLASS="command"
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>anacron</B
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> will make sure that the commands are run at
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the specified intervals as closely as machine-uptime permits.
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</P
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><P
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> <A
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HREF="http://metalab.unc.edu/pub/Linux/system/daemons/cron"
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TARGET="_top"
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>hc-cron</A
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>
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is a modified version of Paul
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Vixie's widely used <B
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CLASS="command"
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>cron</B
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>
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daemon. Like the original program it runs specified jobs at periodic
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intervals. However, the original <B
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CLASS="command"
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>crond</B
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> relies on the
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computer running continuously, otherwise jobs will be missed. This
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problem is addressed by <B
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CLASS="command"
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>hc-cron</B
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>, that is indended for
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use on <EM
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>home-computers</EM
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> that are typically turned off
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several times a day; <B
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CLASS="command"
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>hc-cron</B
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> will remember the time
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when it was shut down and catch up jobs that have occurred during down
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time when it is started again.
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</P
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>Theft Protection</TD
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