anacron

ANACRON(8)                   Anacron Users' Manual                  ANACRON(8)



NAME
       anacron - runs commands periodically

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

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 /usr/local/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).

       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
              /usr/local/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

       -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.

FILES
       /usr/local/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 is currently maintained by Sean 'Shaleh' Perry
       <shaleh@(debian.org|valinux.com)>.



Sean 'Shaleh' Perry               2000-06-22                        ANACRON(8)