Provided by: systemd-cron_1.5.14-2_amd64 bug


       crontab - tables for driving systemd-cron


       A  crontab  file  contains  instructions  to  systemd-cron of the general form: ``run this
       command at this time on this date''.  Each user has their own crontab, and commands in any
       given crontab will be executed as the user who owns the crontab.

       Blank  lines  and  leading  spaces  and  tabs  are  ignored.   Lines whose first non-space
       character is a hash-sign (#) are comments, and are ignored.  Note that  comments  are  not
       allowed  on  the  same  line  as cron commands, since they will be taken to be part of the
       command.  Similarly, comments are not allowed on the same  line  as  environment  variable

       An  active line in a crontab will be either an environment setting or a cron command.  The
       crontab file is parsed from top to bottom, so any environment settings  will  affect  only
       the cron commands below them in the file.  An environment setting is of the form,

           name = value

       where  the  spaces  around the equal-sign (=) are optional, and any subsequent non-leading
       spaces in value will be part of the value assigned to  name.   The  value  string  may  be
       placed  in quotes (single or double, but matching) to preserve leading or trailing blanks.
       The value  string  is  not  parsed  for  environmental  substitutions  or  replacement  of
       variables, thus lines like

           PATH = $HOME/bin:$PATH

       will not work as you might expect. And neither will this work

           C=$A $B

       There will not be any subsitution for the defined variables in the last value.

       An  alternative  for  setting up the commands path is using the fact that many shells will
       treat the tilde(~) as substitution of $HOME, so if you use bash for your tasks you can use


       Special variables:

              Those  are  set  up  automatically  by  systemd  itself,  see systemd.exec(5) SHELL
              defaults to /bin/sh.  SHELL and PATH may be overridden by settings in the crontab.

              On error systemd.cron(7) will look at MAILTO. If MAILTO is defined mail is sent  to
              this  email address.  MAILTO may also be used to direct mail to multiple recipients
              by separating recipient users with  a  comma.   If  MAILTO  is  defined  but  empty
              (MAILTO=""),  no  mail  will  be  sent.  Otherwise mail is sent to the owner of the
              This mail only contains an small excerpt from the log, as seen when using systemctl
              status The full output remains available in the journal.

              (in minutes) environment variable is translated to AccuracySec=.

       DELAY  (in minutes) environment variable is translated to OnBootSec=.  This works like the
              'delay' field of anacrontab(5) and make systemd wait # minutes  after  boot  before
              starting  the  unit.  This  value can also be used to spread out the start times of
              @daily/@weekly/@monthly... jobs on a 24/24 system.

              (in  hours)  environment  variable  is  translated  to  the  ´hour´  component   of
              OnCalendar=.  This variable is inheritted from anacrontab(5), but also supported in
              crontab(5) by systemd-crontab-generator. Anacron expect a time range in the  START-
              END  format (eg: 6-9), systemd-crontab-generator will only use the starting hour of
              the   range   as   reference.    Unless   you   set   this   variable,   all    the
              @daily/@weekly/@monthly/@yearly jobs will run at midnight. If you set this variable
              and the system was off during the ours defined in the range,  the  (persitent)  job
              will start at boot.

              With this flag, you can override the generator default heuristic.
              'yes': force all further jobs to be persistent
              'auto': only recognize @ keywords to be persistent
              'no': force all further jobs not to be persistent

       BATCH  This   boolean   flag   is   translated  to  options  CPUSchedulingPolicy=idle  and
              IOSchedulingClass=idle when set.

       The format of a cron command is the same as the one defined by the cron daemon.  Each line
       has  five  time  and  date  fields, followed by a command, followed by a newline character
       ('\n').  The system crontab (/etc/crontab) and the packages crontabs  (/etc/cron.d/*)  use
       the  same format, except that the username for the command is specified after the time and
       date fields and before the command. The fields may be separated by spaces or tabs.

       Commands are executed by systemd when the minute, hour, and month of year fields match the
       current  time,  and when at least one of the two day fields (day of month, or day of week)
       match the current time (see ``Note'' below).  The time and date fields are:

              field          allowed values
              -----          --------------
              minute         0-59
              hour           0-23
              day of month   1-31
              month          1-12 (or names, see below)
              day of week    0-7 (0 or 7 is Sun, or use names)

       A field may be an asterisk (*), which always stands for ``first-last''.

       Ranges of numbers are allowed.  Ranges are two  numbers  separated  with  a  hyphen.   The
       specified  range  is  inclusive.   For  example,  8-11  for  an  ``hours'' entry specifies
       execution at hours 8, 9, 10 and 11.

       Lists are allowed.  A list is a set of numbers (or ranges) separated by commas.  Examples:
       ``1,2,5,9'', ``0-4,8-12''.

       Step  values can be used in conjunction with ranges.  Following a range with ``/<number>''
       specifies skips of the number's value through the range.  For example, ``0-23/2''  can  be
       used  in the hours field to specify command execution every other hour (the alternative in
       the V7 standard is ``0,2,4,6,8,10,12,14,16,18,20,22'').  Steps are also permitted after an
       asterisk, so if you want to say ``every two hours'', just use ``*/2''.

       Names  can also be used for the ``month'' and ``day of week'' fields.  Use the first three
       letters of the particular day or month (case doesn't matter).  Ranges or  lists  of  names
       are not allowed.

       The  ``sixth''  field  (the rest of the line) specifies the command to be run.  The entire
       command portion of the line, up to a newline , will be executed by /bin/sh or by the shell
       specified in the SHELL variable of the crontab file.

       systemd-crontab-generator  doesn't handle multi-line command split by the % character like

       Note: The day of a command's execution can be specified by two fields — day of month,  and
       day of week.  If both fields are restricted (i.e., aren't *), the command will be run when
       either field matches the current time.  For example,
       ``30 4 1,15 * 5'' would cause a command to be run at 4:30 am on the 1st and 15th  of  each
       month, plus every Friday. One can, however, achieve the desired result by adding a test to
       the command (see the last example in EXAMPLE CRON FILE below).

       Instead of the first five fields, one of eight special strings may appear:

              string         meaning
              ------         -------
              @reboot        Run once, at startup.
              @yearly        Run once a year, "0 0 1 1 *".
              @annually      (same as @yearly)
              @monthly       Run once a month, "0 0 1 * *".
              @weekly        Run once a week, "0 0 * * 0".
              @daily         Run once a day, "0 0 * * *".
              @midnight      (same as @daily)
              @hourly        Run once an hour, "0 * * * *".

       Please note that startup, as far as @reboot  is  concerned,  may  be  before  some  system
       daemons, or other facilities, were startup.  This is due to the boot order sequence of the


       The following lists an example of a user crontab file.

       # use /bin/bash to run commands, instead of the default /bin/sh
       # mail errors to `paul', no matter whose crontab this is
       # run five minutes after midnight, every day
       5 0 * * *       $HOME/bin/daily.job >> $HOME/tmp/out 2>&1
       # run at 2:15pm on the first of every month
       15 14 1 * *     $HOME/bin/monthly
       23 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday"
       5 4 * * sun     echo "run at 5 after 4 every sunday"
       # Run on every second Saturday of the month
       0 4 8-14 * *    test $(date +\%u) -eq 6 && echo "2nd Saturday"


       The following lists the content of a regular system-wide crontab  file.  Unlike  a  user's
       crontab, this file has the username field, as used by /etc/crontab.

       # /etc/crontab: system-wide crontab
       # Unlike any other crontab you don't have to run the `crontab'
       # command to install the new version when you edit this file
       # and files in /etc/cron.d. These files also have username fields,
       # that none of the other crontabs do.


       # m h dom mon dow usercommand
       17 * * * *  root  cd / && run-parts --report /etc/cron.hourly
       25 6 * * *  root  test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )
       47 6 * * 7  root  test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )
       52 6 1 * *  root  test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )

       This is only an example, systemd-cron uses native units instead for those jobs.
       If you add those lines, your jobs will run twice.


       systemd.cron(7), systemd-crontab-generator(8), crontab(1)

       Some extra settings can only be tweaked with

           systemctl edit cron-<schedule>.[timer|service]

       see systemd.cron(7) for more details.


       The  systemd-cron  units  runs with a defined timezone. It currently does not support per-
       user timezones. All the tasks: system's and user's will be run  based  on  the  configured
       timezone.  Even  if  a user specifies the TZ environment variable in his crontab this will
       affect only the commands executed in the crontab, not the execution of the  crontab  tasks

       The  crontab  syntax  does  not  make it possible to define all possible periods one could
       image off. For example, it is not straightforward to define the last weekday of  a  month.
       If  a  task  needs  to  be  run in a specific period of time that cannot be defined in the
       crontab syntaxs the best approach would be to have the program itself check the  date  and
       time information and continue execution only if the period matches the desired one.

       systemd-crontab-generator doesn't support these vixie-cron features:

       *      spawning forking deamons, the 'Service' units are all set with 'Type=oneshot'

       *      multi-line jobs separated by the '%' character

       *      vixie-cron requires that each entry in a crontab end in a newline character. If the
              last entry in a crontab is missing a newline (ie, terminated  by  EOF),  vixie-cron
              will consider the crontab (at least partially) broken.
              systemd-crontab-generator considers this crontab as valid


       You can see how your crontab where translated by typing:
       systemctl cat cron-<userid>-*

       systemctl cat does support command-line completion.


       Paul  Vixie <> is the author of cron and original creator of this manual page.
       This page has also been modified for Debian by Steve Greenland, Javier  Fernandez-Sanguino
       and Christian Kastner.
       This page has been reworded by Alexandre Detiste for inclusion in systemd-cron.