304 lines
9.2 KiB
HTML
304 lines
9.2 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of ANACRON</TITLE>
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</HEAD><BODY>
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<H1>ANACRON</H1>
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Section: Anacron Users' Manual (8)<BR>Updated: 2018-11-30<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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anacron - runs commands periodically
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>anacron </B>[<B>-s</B>] [<B>-f</B>] [<B>-n</B>] [<B>-d</B>] [<B>-q</B>]
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[<B>-t anacrontab</B>] [<B>-S spooldir</B>] [<I>job</I>] ...
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<BR>
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<B>anacron [-S spooldir</B>] -u [<B>-t anacrontab</B>] [<I>job</I>] ...
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<BR>
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<B>anacron </B>[<B>-V</B>|<B>-h</B>]
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<BR>
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<B>anacron -T [-t anacrontab</B>]
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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Anacron
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can be used to execute commands periodically, with a
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frequency specified in days. Unlike <B><A HREF="/cgi-bin/man/man2html?8+cron">cron</A>(8)</B>,
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it does not assume that the machine is running continuously. Hence,
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it can be used on machines that aren't running 24 hours a day,
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to control daily, weekly, and monthly jobs that are
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usually controlled by <B>cron</B>.
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<P>
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When executed, Anacron reads a list of jobs from a configuration file, normally
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<I>/etc/anacrontab</I>
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(see <B><A HREF="/cgi-bin/man/man2html?5+anacrontab">anacrontab</A>(5)</B>). This file
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contains the list of jobs that Anacron controls. Each
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job entry specifies a period in days,
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a delay in minutes, a unique
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job identifier, and a shell command.
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<P>
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For each job, Anacron checks whether
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this job has been executed in the last n days, where n is the period specified
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for that job. If not, Anacron runs the job's shell command, after waiting
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for the number of minutes specified as the delay parameter.
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<P>
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After the command exits, Anacron records the date in a special
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timestamp file for that job, so it can know when to execute it again. Only
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the date is used for the time
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calculations. The hour is not used.
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<P>
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When there are no more jobs to be run, Anacron exits.
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<P>
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Anacron only considers jobs whose identifier, as
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specified in the <I>anacrontab</I> matches any of
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the
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<I>job</I>
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command-line arguments. The
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<I>job</I>
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arguments can be shell wildcard patterns (be sure to protect them from
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your shell with adequate quoting). Specifying no
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<I>job</I>
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arguments, is equivalent to specifying "*" (That is, all jobs will be
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considered).
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<P>
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Unless the <B>-d</B> option is given (see below), Anacron forks to the
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background when it starts, and the parent process exits
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immediately.
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<P>
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Unless the <B>-s</B> or <B>-n</B> options are given, Anacron starts jobs
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immediately when their delay is over. The execution of different jobs is
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completely independent.
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<P>
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If a job generates any output on its standard output or standard error,
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the output is mailed to the user running Anacron (usually root), or to
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the address contained by the MAILTO environment variable in the crontab, if such
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exists.
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<P>
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Informative messages about what Anacron is doing are sent to <B><A HREF="/cgi-bin/man/man2html?8+syslogd">syslogd</A>(8)</B>
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under facility <B>cron</B>, priority <B>notice</B>. Error messages are sent at
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priority <B>error</B>.
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<P>
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"Active" jobs (i.e. jobs that Anacron already decided
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to run and now wait for their delay to pass, and jobs that are currently
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being executed by
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Anacron), are "locked", so that other copies of Anacron won't run them
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at the same time.
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<A NAME="lbAE"> </A>
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<H2>OPTIONS</H2>
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<DL COMPACT>
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<DT id="1"><B>-f</B>
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<DD>
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Force execution of the jobs, ignoring the timestamps.
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<DT id="2"><B>-u</B>
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<DD>
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Only update the timestamps of the jobs, to the current date, but
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don't run anything.
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<DT id="3"><B>-s</B>
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<DD>
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Serialize execution of jobs. Anacron will not start a new job before the
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previous one finished.
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<DT id="4"><B>-n</B>
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<DD>
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Run jobs now. Ignore the delay specifications in the
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<I>/etc/anacrontab</I>
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file. This options implies <B>-s</B>.
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<DT id="5"><B>-d</B>
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<DD>
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Don't fork to the background. In this mode, Anacron will output informational
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messages to standard error, as well as to syslog. The output of jobs
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is mailed as usual.
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<DT id="6"><B>-q</B>
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<DD>
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Suppress messages to standard error. Only applicable with <B>-d</B>.
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<DT id="7"><B>-t anacrontab</B>
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<DD>
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Use specified anacrontab, rather than the default
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<DT id="8"><B>-T</B>
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<DD>
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Anacrontab testing. The configuration file will be tested for validity. If
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there is an error in the file, an error will be shown and anacron will
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return 1. Valid anacrontabs will return 0.
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<DT id="9"><B>-S spooldir</B>
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<DD>
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Use the specified spooldir to store timestamps in. This option is required for
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users who wish to run anacron themselves.
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<DT id="10"><B>-V</B>
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<DD>
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Print version information, and exit.
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<DT id="11"><B>-h</B>
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<DD>
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Print short usage message, and exit.
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</DL>
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<A NAME="lbAF"> </A>
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<H2>SIGNALS</H2>
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After receiving a <B>SIGUSR1</B> signal, Anacron waits for running
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jobs, if any, to finish and then exits. This can be used to stop
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Anacron cleanly.
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<A NAME="lbAG"> </A>
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<H2>NOTES</H2>
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Make sure that the time-zone is set correctly before Anacron is
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started. (The time-zone affects the date). This is usually accomplished
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by setting the TZ environment variable, or by installing a
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<I>/usr/lib/zoneinfo/localtime</I>
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file. See
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<B><A HREF="/cgi-bin/man/man2html?3+tzset">tzset</A>(3)</B>
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for more information.
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<P>
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Timestamp files are created in the spool directory for each job in anacrontab.
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These are never removed automatically by anacron, and should be removed by
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hand if a job is no longer being scheduled.
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<A NAME="lbAH"> </A>
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<H2>DEBIAN-SPECIFIC CONFIGURATION</H2>
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<P>
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On Debian-based systems, anacron will be activated hourly every day from 07:30
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local time to 23:30 local time through cron job (on non-systemd systems where
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cron is installed and enabled) or systemd timer (on systemd-based systems).
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On activation, anacron will check if it missed some jobs. If yes, it will start
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those jobs after a short period of time.
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<P>
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By default,
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The hourly activation of anacron will not take place
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when the system is using battery and no AC power is
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connected to the computer. It is meant to reduce power usage and extend
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battery life, but such design might lead to unwanted results.
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Users may disable this feature and let anacron run regardless of power
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supply. Please read Debian-specific documentation in
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<I>/usr/share/doc/anacron/README.Debian</I>
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file for detailed instruction in now to change such behaviour.
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<A NAME="lbAI"> </A>
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<H2>FILES</H2>
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<DL COMPACT>
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<DT id="12"><I>/etc/anacrontab</I>
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<DD>
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Contains specifications of jobs. See <B><A HREF="/cgi-bin/man/man2html?5+anacrontab">anacrontab</A>(5)</B> for a complete
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description.
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<DT id="13"><I>/var/spool/anacron</I>
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<DD>
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This directory is used by Anacron for storing timestamp files.
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<DT id="14"><I>/lib/systemd/system/anacron.service</I>
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<DD>
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This file provides systemd service for anacron.
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<DT id="15"><I>/lib/systemd/system/anacron.timer</I>
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<DD>
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This file provides systemd timer for anacron. Currently the service is
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triggered hourly through systemd timer.
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</DL>
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<A NAME="lbAJ"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?5+anacrontab">anacrontab</A>(5), <A HREF="/cgi-bin/man/man2html?8+cron">cron</A>(8), <A HREF="/cgi-bin/man/man2html?3+tzset">tzset</A>(3)</B>
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<P>
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The Anacron
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<I>README</I>
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file.
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<P>
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For Debian-specific modifications, please read
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<I>/usr/share/doc/anacron/README.Debian</I>
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file for detailed information.
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<A NAME="lbAK"> </A>
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<H2>BUGS</H2>
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Anacron never removes timestamp files. Remove unused files manually.
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<P>
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Anacron
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uses up to two file descriptors for each active job. It may run out of
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descriptors if there are more than about 125 active jobs (on normal kernels).
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<P>
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Mail comments, suggestions and bug reports to Sean 'Shaleh' Perry <shaleh@(debian.org|valinux.com)>.
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<A NAME="lbAL"> </A>
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<H2>AUTHOR</H2>
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Anacron was originally conceived and implemented by Christian Schwarz
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<<A HREF="mailto:schwarz@monet.m.isar.de">schwarz@monet.m.isar.de</A>>. The current implementation is a complete rewrite by
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Itai Tzur <<A HREF="mailto:itzur@actcom.co.il">itzur@actcom.co.il</A>>.
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<P>
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The code base was maintained by Sean 'Shaleh' Perry <shaleh@(debian.org|valinux.com)>.
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During 2004-2006, it was maintained by Pascal Hakim <pasc@(debian.org|redellipse.net)>.
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During 2009-2014, it was maintained by Peter Eisentraut <<A HREF="mailto:petere@debian.org">petere@debian.org</A>>.
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<P>
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Nowadays anacron in Debian is co-maintained by various developers
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from Debian Project.
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="16"><A HREF="#lbAB">NAME</A><DD>
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<DT id="17"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="18"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="19"><A HREF="#lbAE">OPTIONS</A><DD>
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<DT id="20"><A HREF="#lbAF">SIGNALS</A><DD>
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<DT id="21"><A HREF="#lbAG">NOTES</A><DD>
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<DT id="22"><A HREF="#lbAH">DEBIAN-SPECIFIC CONFIGURATION</A><DD>
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<DT id="23"><A HREF="#lbAI">FILES</A><DD>
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<DT id="24"><A HREF="#lbAJ">SEE ALSO</A><DD>
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<DT id="25"><A HREF="#lbAK">BUGS</A><DD>
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<DT id="26"><A HREF="#lbAL">AUTHOR</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:06:10 GMT, March 31, 2021
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</BODY>
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</HTML>
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