168 lines
6.0 KiB
Groff
168 lines
6.0 KiB
Groff
.TH ANACRON 8 2009-07-17 "Marcela Mašláňová" "Anacron Users' Manual"
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.SH NAME
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anacron \- runs commands periodically
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.SH SYNOPSIS
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.B anacron \fR[\fB-s\fR] [\fB-f\fR] [\fB-n\fR] [\fB-d\fR] [\fB-q\fR]
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[\fB-t anacrontab\fR] [\fB-S spooldir\fR] [\fIjob\fR]
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.br
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.B anacron \fR[\fB-S spooldir\fR] -u [\fB-t anacrontab\fR] \fR[\fIjob\fR]
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.br
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.B anacron \fR[\fB-V\fR|\fB-h\fR]
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.br
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.B anacron -T \fR[\fB-t anacrontab\fR]
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.SH DESCRIPTION
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Anacron
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is used to execute commands periodically, with a
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frequency specified in days. Unlike \fBcron(8)\fR,
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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 are not running 24 hours a day
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to control regular jobs as daily, weekly, and monthly jobs.
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.PP
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Anacron reads a list of jobs from the
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.I /etc/anacrontab
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configuration file (see \fBanacrontab(5)\fR). 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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.PP
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For each job, Anacron checks whether
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this job has been executed in the last \fBn\fR days, where \fBn\fR is the time period specified
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for that job. If a job has not been executed in \fBn\fR days or more, 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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.PP
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After the command exits, Anacron records the date (excludes the hour) in a special
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timestamp file for that job, so it knows when to execute that job again.
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.PP
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When there are no more jobs to be run, Anacron exits.
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.PP
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Anacron only considers jobs whose identifier, as
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specified in \fBanacrontab(5)\fR, matches any of
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the
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.I job
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command-line arguments. The
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.I job
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command-line arguments can be represented by 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
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command-line arguments is equivalent to specifying "*" (that is, all jobs are
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considered by Anacron).
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.PP
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Unless Anacron is run with the \fB-d\fR option (specified below), it forks to the
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background when it starts, and any parent processes exit immediately.
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.PP
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Unless Anacron is run with the \fB-s\fR or \fB-n\fR options, it 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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.PP
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If an executed job generates any output to standard output or to standard error,
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the output is mailed to the user under whom Anacron is running (usually root), or to
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the address specified in the \fBMAILTO\fR environment variable in the
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.I /etc/anacrontab
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file, if such exists. If the \fBLOGNAME\fR environment variable is set, it is used in the From: field of the mail.
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.PP
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Any informative messages generated by Anacron are sent to \fBsyslogd(8)\fR
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or \fBrsyslogd(8)\fR under with facility set to \fBcron\fR and priority set to \fBnotice\fR. Any error
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messages are sent with the priority \fBerror\fR.
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.PP
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"Active" jobs (i.e. jobs that Anacron already decided
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to run and are now waiting 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 cannot run them
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at the same time.
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.SH OPTIONS
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.TP
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.B -f
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Forces execution of all jobs, ignoring any timestamps.
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.TP
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.B -u
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Updates the timestamps of all jobs to the current date, but
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does not run any.
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.TP
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.B -s
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Serializes execution of jobs. Anacron does not start a new job before the
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previous one finished.
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.TP
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.B -n
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Runs jobs immediately and ignores the specified delays in the
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.I /etc/anacrontab
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file. This options implies \fB-s\fR.
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.TP
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.B -d
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Does not fork Anacron 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 any job
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is mailed by Anacron.
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.TP
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.B -q
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Suppresses any messages to standard error. Only applicable with \fB-d\fR.
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.TP
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.B -t some_anacrontab
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Uses the specified anacrontab, rather than the
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.I /etc/anacrontab
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default one.
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.TP
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.B -T
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Anacrontab testing. Tests the
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.I /etc/anacrontab
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configuration file for validity. If
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there is an error in the file, it is shown on the standard output and Anacron
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returns the value of 1. Valid anacrontabs return the value of 0.
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.TP
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.B -S spooldir
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Uses 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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.TP
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.B -V
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Prints version information, and exits.
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.TP
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.B -h
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Prints short usage message, and exits.
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.SH SIGNALS
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After receiving a \fBSIGUSR1\fR signal, Anacron waits for any running
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jobs to finish and then exits. This can be used to stop
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Anacron cleanly.
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.SH NOTES
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Make sure your time-zone is set correctly before Anacron is
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started since 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
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file. See
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.B tzset(3)
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for more information.
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Timestamp files are created in the spool directory for each job specified in an anacrontab. These files are never removed automatically by Anacron, and should be removed by hand if a job is no longer being scheduled.
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.SH FILES
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.TP
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.I /etc/anacrontab
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Contains specifications of jobs. See \fBanacrontab(5)\fR for a complete
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description.
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.TP
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.I /var/spool/anacron
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This directory is used by Anacron for storing timestamp files.
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.SH "SEE ALSO"
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.BR anacrontab (5), cron (8), tzset (3)
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.PP
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The Anacron
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.I README
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file.
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.SH BUGS
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Anacron never removes timestamp files. Remove unused files manually.
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.PP
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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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.PP
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Mail comments, suggestions and bug reports to Sean 'Shaleh' Perry <shaleh@(debian.org|valinux.com)>.
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.SH AUTHOR
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Anacron was originally conceived and implemented by Christian Schwarz
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<schwarz@monet.m.isar.de>.
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.PP
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The current implementation is a complete rewrite by Itai Tzur
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<itzur@actcom.co.il>.
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.PP
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The code base was maintained by Sean 'Shaleh' Perry <shaleh@(debian.org|valinux.com)>.
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.PP
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Since 2004, it is maintained by Pascal Hakim <pasc@(debian.org|redellipse.net)>.
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.PP
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For Fedora, Anacron is maintained by Marcela Mašláňová <mmaslano@redhat.com>.
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