anacron(8)

NAME

   anacron - runs commands periodically

SYNOPSIS

   anacron  [-s]  [-f]  [-n] [-d] [-q] [-t anacrontab] [-S spooldir] [job]
   ...
   anacron [-S spooldir] -u [-t anacrontab] [job] ...
   anacron [-V|-h]
   anacron -T [-t anacrontab]

DESCRIPTION

   Anacron can be used to execute commands periodically, with a  frequency
   specified in days.  Unlike cron(8), it does not assume that the machine
   is running continuously.  Hence, it can be used on machines that aren't
   running 24 hours a day, to control daily, weekly, and monthly jobs that
   are usually controlled by cron.

   When executed, Anacron reads a list of jobs from a configuration  file,
   normally  /etc/anacrontab  (see 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.

   For each job, Anacron checks whether this job has been executed in  the
   last  n  days,  where  n is the period specified for that job.  If not,
   Anacron runs the job's shell command, after waiting for the  number  of
   minutes specified as the delay parameter.

   After  the  command  exits,  Anacron  records  the  date  in  a special
   timestamp file for that job, so it can know when to execute  it  again.
   Only the date is used for the time calculations.  The hour is not used.

   When there are no more jobs to be run, Anacron exits.

   Anacron  only  considers  jobs  whose  identifier,  as specified in the
   anacrontab matches any of the  job  command-line  arguments.   The  job
   arguments  can be shell wildcard patterns (be sure to protect them from
   your shell with adequate quoting).  Specifying  no  job  arguments,  is
   equivalent to specifying "*"  (That is, all jobs will be considered).

   Unless  the  -d  option  is  given  (see  below),  Anacron forks to the
   background when it starts, and the parent process exits immediately.

   Unless the -s or -n options are given, Anacron starts jobs  immediately
   when  their  delay  is  over.   The  execution  of  different  jobs  is
   completely independent.

   If a job generates any output on its standard output or standard error,
   the  output is mailed to the user running Anacron (usually root), or to
   the address  contained  by  the  MAILTO  environment  variable  in  the
   crontab, if such exists.

   Informative messages about what Anacron is doing are sent to syslogd(8)
   under facility cron, priority  notice.   Error  messages  are  sent  at
   priority error.

   "Active"  jobs  (i.e.  jobs that Anacron already decided to run and now
   wait for their delay  to  pass,  and  jobs  that  are  currently  being
   executed  by  Anacron),  are  "locked", so that other copies of Anacron
   won't run them at the same time.

OPTIONS

   -f     Force execution of the jobs, ignoring the timestamps.

   -u     Only update the timestamps of the jobs, to the current date, but
          don't run anything.

   -s     Serialize  execution  of jobs.  Anacron will not start a new job
          before the previous one finished.

   -n     Run  jobs  now.   Ignore  the  delay   specifications   in   the
          /etc/anacrontab file.  This options implies -s.

   -d     Don't fork to the background.  In this mode, Anacron will output
          informational messages to standard error, as well as to  syslog.
          The output of jobs is mailed as usual.

   -q     Suppress messages to standard error.  Only applicable with -d.

   -t anacrontab
          Use specified anacrontab, rather than the default

   -T     Anacrontab  testing.  The  configuration file will be tested for
          validity. If there is an error in the file,  an  error  will  be
          shown  and  anacron will return 1. Valid anacrontabs will return
          0.

   -S spooldir
          Use the specified spooldir to store timestamps in.  This  option
          is required for users who wish to run anacron themselves.

   -V     Print version information, and exit.

   -h     Print short usage message, and exit.

SIGNALS

   After  receiving  a  SIGUSR1 signal, Anacron waits for running jobs, if
   any, to finish and then exits.   This  can  be  used  to  stop  Anacron
   cleanly.

NOTES

   Make  sure  that  the  time-zone  is  set  correctly  before Anacron is
   started.   (The  time-zone  affects  the  date).    This   is   usually
   accomplished by setting the TZ environment variable, or by installing a
   /usr/lib/zoneinfo/localtime file.  See tzset(3) for more information.

   Timestamp files are created in the spool  directory  for  each  job  in
   anacrontab.  These  are  never  removed  automatically  by anacron, and
   should be removed by hand if a job is no longer being scheduled.

FILES

   /etc/anacrontab
          Contains  specifications  of  jobs.   See  anacrontab(5)  for  a
          complete description.

   /var/spool/anacron
          This directory is used by Anacron for storing timestamp files.

SEE ALSO

   anacrontab(5), cron(8), tzset(3)

   The Anacron README file.

BUGS

   Anacron never removes timestamp files.  Remove unused files manually.

   Anacron  uses  up  to two file descriptors for each active job.  It may
   run out of descriptors if there are more than about 125 active jobs (on
   normal kernels).

   Mail  comments,  suggestions  and  bug  reports  to Sean 'Shaleh' Perry
   <shaleh@(debian.org|valinux.com)>.

AUTHOR

   Anacron was originally conceived and implemented by  Christian  Schwarz
   <schwarz@monet.m.isar.de>.

   The   current  implementation  is  a  complete  rewrite  by  Itai  Tzur
   <itzur@actcom.co.il>.

   The   code   base   was   maintained    by    Sean    'Shaleh'    Perry
   <shaleh@(debian.org|valinux.com)>.

   Since     2004,     it     is     maintained     by     Pascal    Hakim
   <pasc@(debian.org|redellipse.net)>.

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