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cron(8)

System Administration Commands                                         cron(8)



NAME
       cron - clock daemon

SYNOPSIS
       /usr/sbin/cron

DESCRIPTION
       cron  starts  a  process  that executes commands at specified dates and
       times.


       You can specify regularly  scheduled  commands  to  cron  according  to
       instructions    found    in    crontab    files    in   the   directory
       /var/spool/cron/crontabs. Users can submit their own crontab file using
       the crontab(1) command. Commands which are to be executed only once can
       be submitted using the at(1) command.


       cron only examines crontab or at command files during its  own  process
       initialization  phase  and  when the crontab or at command is run. This
       reduces the overhead of checking for new or changed files at  regularly
       scheduled intervals.


       As cron never exits, it should be executed only once. This is done rou‐
       tinely  by  way  of  the  svc:/system/cron:default  service.  The  file
       /etc/cron.d/FIFO  file  is used as a lock file to prevent the execution
       of more than one instance of cron.


       cron captures the output of the job's stdout and stderr  streams,  and,
       if  it  is not empty, mails the output to the user. If the job does not
       produce output, no mail is sent to the user. An exception is if the job
       is  an  at(1) job and the -m option was specified when the job was sub‐
       mitted.


       cron and at jobs are not executed if your account is locked or expired.
       Consult  shadow(5)  to  determine which accounts are not locked and not
       expired.

   Setting cron Jobs Across Timezones
       The timezone of the cron daemon sets the system-wide timezone for  cron
       entries.  This,  in  turn,  is  by  set  by  default  system-wide using
       /etc/default/init. The timezone for cron entries can be overridden in a
       user's crontab file; see crontab(1).


       If  some  form  of daylight savings or summer/winter time is in effect,
       then jobs scheduled during the  switchover  period  could  be  executed
       once, twice, or not at all.

   Setting cron Defaults
       To  keep  a  log  of  all actions taken by cron, you must specify CRON‐
       LOG=YES in the /etc/default/cron file. If you  specify  CRONLOG=NO,  no
       logging  is  done.  Keeping the log is a user configurable option since
       cron usually creates huge log files.


       You can specify  the  PATH  for  user  cron  jobs  by  using  PATH=  in
       /etc/default/cron.  You  can  set  the  PATH  for  root cron jobs using
       SUPATH= in /etc/default/cron. Carefully consider the security  implica‐
       tions of setting PATH and SUPATH.


       Example /etc/default/cron file:



         CRONLOG=YES
         PATH=/usr/bin



       This example enables logging and sets the default PATH used by non-root
       jobs to /usr/bin. Root jobs continue to use /usr/bin.


       The cron log file is periodically rotated by logadm(8).

FILES
       /etc/cron.d              Main cron directory


       /etc/cron.d/FIFO         Lock file


       /etc/default/cron        cron default settings file


       /var/cron/log            cron history information


       /var/spool/cron          Spool area


       /etc/cron.d/queuedefs    Queue description file for at, batch, and cron


       /etc/logadm.conf         Configuration file for logadm


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i)


       ATTRIBUTE TYPEATTRIBUTE VALUE _ Availabilitysystem/core-os


SEE ALSO
       at(1),   crontab(1),   sh(1),   svcs(1),    queuedefs(5),    shadow(5),
       attributes(7), rbac(7), smf(7), smf_security(7), logadm(8), svcadm(8)

NOTES
       A  cron  job is executed in a separate invocation of the shell, running
       in a separate process group with no  controlling  terminal.  Open  file
       descriptors, traps and priority inherited from the invoking environment
       are lost.


       The cron service is managed by the service management facility, smf(7),
       under the service identifier:

         svc:/system/cron:default



       Administrative actions on this service, such as enabling, disabling, or
       requesting restart, can be performed  using  svcadm(8).  The  service's
       status  can  be  queried using the svcs(1) command. Most administrative
       actions may be delegated  to  users  with  the  solaris.smf.manage.cron
       authorization (see rbac(7) and smf_security(7)).

DIAGNOSTICS
       A  history  of all actions taken by cron is stored in /var/cron/log and
       possibly in /var/cron/olog.



Oracle Solaris 11.4               23 Jan 2017                          cron(8)
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