1 .\"/* Copyright 1988,1990,1993,1994 by Paul Vixie
2 .\" * All rights reserved
4 .\" * Distribute freely, except: don't remove my name from the source or
5 .\" * documentation (don't take credit for my work), mark your changes (don't
6 .\" * get me blamed for your possible bugs), don't alter or remove this
7 .\" * notice. May be sold if buildable source is provided to buyer. No
8 .\" * warrantee of any kind, express or implied, is included with this
9 .\" * software; use at your own risk, responsibility for damages (if any) to
10 .\" * anyone resulting from the use of this software rests entirely with the
13 .\" * Send bug reports, bug fixes, enhancements, requests, flames, etc., and
14 .\" * I'll try to keep a version up to date. I can be reached as follows:
15 .\" * Paul Vixie <paul@vix.com> uunet!decwrl!vixie!paul
18 .\" $FreeBSD: src/usr.sbin/cron/crontab/crontab.5,v 1.12.2.8 2002/12/29 16:35:41 schweikh Exp $
19 .\" $DragonFly: src/usr.sbin/cron/crontab/crontab.5,v 1.2 2003/06/17 04:29:53 dillon Exp $
26 .Nd tables for driving cron
30 file contains instructions to the
32 daemon of the general form: ``run this command at this time on this date''.
33 Each user has their own crontab, and commands in any given crontab will be
34 executed as the user who owns the crontab. Uucp and News will usually have
35 their own crontabs, eliminating the need for explicitly running
37 as part of a cron command.
39 Blank lines and leading spaces and tabs are ignored. Lines whose first
40 non-space character is a pound-sign (#) are comments, and are ignored.
41 Note that comments are not allowed on the same line as cron commands, since
42 they will be taken to be part of the command. Similarly, comments are not
43 allowed on the same line as environment variable settings.
45 An active line in a crontab will be either an environment setting or a cron
46 command. An environment setting is of the form,
51 where the spaces around the equal-sign (=) are optional, and any subsequent
54 will be part of the value assigned to
58 string may be placed in quotes (single or double, but matching) to preserve
59 leading or trailing blanks.
62 string may also be placed in quote (single or double, but matching)
63 to preserve leading, trailing or inner blanks.
65 Several environment variables are set up
78 line of the crontab's owner.
82 may be overridden by settings in the crontab;
88 variable is sometimes called
105 if it has any reason to send mail as a result of running
106 commands in ``this'' crontab. If
108 is defined (and non-empty), mail is
109 sent to the user so named. If
111 is defined but empty (MAILTO=""), no
112 mail will be sent. Otherwise mail is sent to the owner of the crontab. This
113 option is useful if you decide on
116 .Pa /usr/lib/sendmail
118 your mailer when you install cron --
120 doesn't do aliasing, and UUCP
121 usually doesn't read its mail.
123 The format of a cron command is very much the V7 standard, with a number of
124 upward-compatible extensions. Each line has five time and date fields,
125 followed by a user name
126 (with optional ``:<group>'' and ``/<login-class>'' suffixes)
127 if this is the system crontab file,
128 followed by a command. Commands are executed by
130 when the minute, hour, and month of year fields match the current time,
132 when at least one of the two day fields (day of month, or day of week)
133 matches the current time (see ``Note'' below).
135 examines cron entries once every minute.
136 The time and date fields are:
137 .Bd -literal -offset indent
143 month 1-12 (or names, see below)
144 day of week 0-7 (0 or 7 is Sun, or use names)
147 A field may be an asterisk (*), which always stands for ``first\-last''.
149 Ranges of numbers are allowed. Ranges are two numbers separated
150 with a hyphen. The specified range is inclusive. For example,
151 8-11 for an ``hours'' entry specifies execution at hours 8, 9, 10
154 Lists are allowed. A list is a set of numbers (or ranges)
155 separated by commas. Examples: ``1,2,5,9'', ``0-4,8-12''.
157 Step values can be used in conjunction with ranges. Following
158 a range with ``/<number>'' specifies skips of the number's value
159 through the range. For example, ``0-23/2'' can be used in the hours
160 field to specify command execution every other hour (the alternative
161 in the V7 standard is ``0,2,4,6,8,10,12,14,16,18,20,22''). Steps are
162 also permitted after an asterisk, so if you want to say ``every two
163 hours'', just use ``*/2''.
165 Names can also be used for the ``month'' and ``day of week''
166 fields. Use the first three letters of the particular
167 day or month (case doesn't matter). Ranges or
168 lists of names are not allowed.
170 The ``sixth'' field (the rest of the line) specifies the command to be
172 The entire command portion of the line, up to a newline or %
173 character, will be executed by
178 variable of the cronfile.
179 Percent-signs (%) in the command, unless escaped with backslash
180 (\\), will be changed into newline characters, and all data
181 after the first % will be sent to the command as standard
184 Note: The day of a command's execution can be specified by two
185 fields \(em day of month, and day of week. If both fields are
186 restricted (ie, aren't *), the command will be run when
188 field matches the current time. For example,
190 would cause a command to be run at 4:30 am on the 1st and 15th of each
191 month, plus every Friday.
193 Instead of the first five fields,
194 one of eight special strings may appear:
195 .Bd -literal -offset indent
198 @reboot Run once, at startup.
199 @yearly Run once a year, "0 0 1 1 *".
200 @annually (same as @yearly)
201 @monthly Run once a month, "0 0 1 * *".
202 @weekly Run once a week, "0 0 * * 0".
203 @daily Run once a day, "0 0 * * *".
204 @midnight (same as @daily)
205 @hourly Run once an hour, "0 * * * *".
207 .Sh EXAMPLE CRON FILE
210 # use /bin/sh to run commands, overriding the default set by cron
212 # mail any output to `paul', no matter whose crontab this is
215 # run five minutes after midnight, every day
216 5 0 * * * $HOME/bin/daily.job >> $HOME/tmp/out 2>&1
217 # run at 2:15pm on the first of every month -- output mailed to paul
218 15 14 1 * * $HOME/bin/monthly
219 # run at 10 pm on weekdays, annoy Joe
220 0 22 * * 1-5 mail -s "It's 10pm" joe%Joe,%%Where are your kids?%
221 23 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday"
222 5 4 * * sun echo "run at 5 after 4 every sunday"
228 When specifying day of week, both day 0 and day 7 will be considered Sunday.
232 seem to disagree about this.
234 Lists and ranges are allowed to co-exist in the same field. "1-3,7-9" would
239 cron -- they want to see "1-3" or "7,8,9" ONLY.
241 Ranges can include "steps", so "1-9/2" is the same as "1,3,5,7,9".
243 Names of months or days of the week can be specified by name.
245 Environment variables can be set in the crontab. In
250 environment handed to child processes is basically the one from
253 Command output is mailed to the crontab owner
255 can't do this), can be
256 mailed to a person other than the crontab owner (SysV can't do this), or the
257 feature can be turned off and no mail will be sent at all (SysV can't do this
262 commands that can appear in place of the first five fields
265 .An Paul Vixie Aq paul@vix.com
267 If you're in one of the 70-odd countries that observe Daylight
268 Savings Time, jobs scheduled during the rollback or advance will be
269 affected. In general, it's not a good idea to schedule jobs during
272 For US timezones (except parts of IN, AZ, and HI) the time shift occurs at
273 2AM local time. For others, the output of the
277 option can be used to determine the moment of time shift.