root/man/anacron.8

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.TH ANACRON 8 2012-11-22 "cronie" "System Administration"
.SH NAME
anacron \- runs commands periodically
.SH SYNOPSIS
.B anacron \fR[\fB-s\fR] [\fB-f\fR] [\fB-n\fR] [\fB-d\fR] [\fB-q\fR]
[\fB-t anacrontab\fR] [\fB-S spooldir\fR] [\fIjob\fR]
.br
.B anacron \fR[\fB-S spooldir\fR] -u [\fB-t anacrontab\fR] \fR[\fIjob\fR]
.br
.B anacron \fR[\fB-V\fR|\fB-h\fR]
.br
.B anacron -T \fR[\fB-t anacrontab\fR]
.SH DESCRIPTION
.B Anacron
is used to execute commands periodically, with a frequency specified in
days.  Unlike
.BR cron(8) ,
it does not assume that the machine is running continuously.  Hence, it
can be used on machines that are not running 24 hours a day to control
regular jobs as daily, weekly, and monthly jobs.
.PP
Anacron reads a list of jobs from the
.I /etc/anacrontab
configuration file (see
.BR anacrontab (5)).
This file contains the list of jobs that Anacron controls.  Each job
entry specifies a period in days, a delay in minutes, a unique job
identifier, and a shell command.
.PP
For each job, Anacron checks whether this job has been executed in the
last
.B n
days, where
.B n
is the time period specified for that job.  If a job has not been
executed in
.B n
days or more, Anacron runs the job's shell command, after waiting for the
number of minutes specified as the delay parameter.
.PP
After the command exits, Anacron records the date (excludes the hour) in
a special timestamp file for that job, so it knows when to execute that
job again.
.PP
When there are no more jobs to be run, Anacron exits.
.PP
Anacron only considers jobs whose identifier, as specified in
.BR anacrontab (5),
matches any of the
.I job
command-line arguments.  The
.I job
command-line arguments can be represented by shell wildcard patterns (be
sure to protect them from your shell with adequate quoting).  Specifying
no
.I job
command-line arguments is equivalent to specifying "*"  (that is, all
jobs are considered by Anacron).
.PP
Unless Anacron is run with the
.B \-d
option (specified below), it forks to the background when it starts, and
any parent processes exit immediately.
.PP
Unless Anacron is run with the
.B \-s
or
.B \-n
options, it starts jobs immediately when their delay is over.  The
execution of different jobs is completely independent.
.PP
If an executed job generates any output to standard output or to standard
error, the output is mailed to the user under whom Anacron is running
(usually root), or to the address specified in the
.B MAILTO
environment variable in the
.I /etc/anacrontab
file, if such exists.  If the
.B LOGNAME
environment variable is set, it is used in the From: field of the mail.
.PP
Any informative messages generated by Anacron are sent to
.BR syslogd (8)
or
.BR rsyslogd (8)
under with facility set to
.B cron
and priority set to
.BR notice .
Any error messages are sent with the priority
.BR error .
.PP
"Active" jobs (i.e., jobs that Anacron already decided to run and are now
waiting for their delay to pass, and jobs that are currently being
executed by Anacron), are "locked", so that other copies of Anacron
cannot run them at the same time.
.SH OPTIONS
.TP
.B \-f
Forces execution of all jobs, ignoring any timestamps.
.TP
.B \-u
Updates the timestamps of all jobs to the current date, but does not run
any.
.TP
.B \-s
Serializes execution of jobs.  Anacron does not start a new job before the
previous one finished.
.TP
.B \-n
Runs jobs immediately and ignores the specified delays in the
.I /etc/anacrontab
file.  This options implies
.BR -s .
.TP
.B \-d
Does not fork Anacron to the background.  In this mode, Anacron will
output informational messages to standard error, as well as to syslog.
The output of any job is mailed by Anacron.
.TP
.B \-q
Suppresses any messages to standard error.  Only applicable with
.BR -d .
.TP
.B -t some_anacrontab
Uses the specified anacrontab, rather than the
.I /etc/anacrontab
default one.
.TP
.B -T
Anacrontab testing. Tests the
.I /etc/anacrontab
configuration file for validity. If there is an error in the file, it is
shown on the standard output and Anacron returns the value of 1.  Valid
anacrontabs return the value of 0.
.TP
.B -S spooldir
Uses the specified spooldir to store timestamps in.  This option is
required for users who wish to run anacron themselves.
.TP
.B -V
Prints version information, and exits.
.TP
.B -h
Prints short usage message, and exits.
.SH SIGNALS
After receiving a
.B SIGUSR1
signal, Anacron waits for any running jobs to finish and then exits.
This can be used to stop Anacron cleanly.
.SH NOTES
Make sure your time-zone is set correctly before Anacron is started since
the time-zone affects the date.  This is usually accomplished by setting
the TZ environment variable, or by installing a
.I /usr/lib/zoneinfo/localtime
file.  See
.BR tzset (3)
for more information.
.PP
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.
.SH FILES
.TP
.I /etc/anacrontab
Contains specifications of jobs.  See
.BR anacrontab (5)
for a complete description.
.TP
.I /var/spool/anacron
This directory is used by Anacron for storing timestamp files.
.SH "SEE ALSO"
.BR anacrontab (5),
.BR cron (8),
.BR tzset (3)
.PP
The Anacron
.I README
file.
.SH BUGS
Anacron never removes timestamp files.  Remove unused files manually.
.PP
Anacron uses up to two file descriptors for each active job.  It may run
out of descriptors if there are lots of active jobs.  See
.B echo $(($(ulimit -n) / 2))
for information how many concurent jobs anacron may run.
.PP
Mail comments, suggestions and bug reports to
.MT shaleh@\:(debian.\:org|\:valinux.\:com)
Sean 'Shaleh' Perry
.ME .
.SH AUTHOR
Anacron was originally conceived and implemented by
.MT schwarz@\:monet.\:m.\:isar.\:de
Christian Schwarz
.ME .
.PP
The current implementation is a complete rewrite by
.MT itzur@\:actcom.\:co.\:il
Itai Tzur
.ME .
.PP
The code base was maintained by
.MT shaleh@\:(debian.\:org|\:valinux.\:com)
Sean 'Shaleh' Perry
.ME .
.PP
Since 2004, it is maintained by
.MT pasc@\:(debian.\:org|\:redellipse.\:net)
Pascal Hakim
.ME .
.PP
For Fedora, Anacron is maintained by
.MT mmaslano@redhat.\:com
Marcela Mašláňová
.ME .

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