1.\"/* Copyright 1988,1990,1993,1994 by Paul Vixie 2.\" * All rights reserved 3.\" * 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 11.\" * user. 12.\" * 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 16.\" */ 17.\" 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 $ 20.\" 21.Dd January 24, 1994 22.Dt CRONTAB 5 23.Os 24.Sh NAME 25.Nm crontab 26.Nd tables for driving cron 27.Sh DESCRIPTION 28A 29.Nm 30file contains instructions to the 31.Xr cron 8 32daemon of the general form: ``run this command at this time on this date''. 33Each user has their own crontab, and commands in any given crontab will be 34executed as the user who owns the crontab. Uucp and News will usually have 35their own crontabs, eliminating the need for explicitly running 36.Xr su 1 37as part of a cron command. 38.Pp 39Blank lines and leading spaces and tabs are ignored. Lines whose first 40non-space character is a pound-sign (#) are comments, and are ignored. 41Note that comments are not allowed on the same line as cron commands, since 42they will be taken to be part of the command. Similarly, comments are not 43allowed on the same line as environment variable settings. 44.Pp 45An active line in a crontab will be either an environment setting or a cron 46command. An environment setting is of the form, 47.Bd -literal 48 name = value 49.Ed 50.Pp 51where the spaces around the equal-sign (=) are optional, and any subsequent 52non-leading spaces in 53.Em value 54will be part of the value assigned to 55.Em name . 56The 57.Em value 58string may be placed in quotes (single or double, but matching) to preserve 59leading or trailing blanks. 60The 61.Em name 62string may also be placed in quote (single or double, but matching) 63to preserve leading, trailing or inner blanks. 64.Pp 65Several environment variables are set up 66automatically by the 67.Xr cron 8 68daemon. 69.Ev SHELL 70is set to 71.Pa /bin/sh , 72and 73.Ev LOGNAME 74and 75.Ev HOME 76are set from the 77.Pa /etc/passwd 78line of the crontab's owner. 79.Ev HOME 80and 81.Ev SHELL 82may be overridden by settings in the crontab; 83.Ev LOGNAME 84may not. 85.Pp 86(Another note: the 87.Ev LOGNAME 88variable is sometimes called 89.Ev USER 90on 91.Bx 92systems... 93On these systems, 94.Ev USER 95will be set also). 96.Pp 97In addition to 98.Ev LOGNAME , 99.Ev HOME , 100and 101.Ev SHELL , 102.Xr cron 8 103will look at 104.Ev MAILTO 105if it has any reason to send mail as a result of running 106commands in ``this'' crontab. If 107.Ev MAILTO 108is defined (and non-empty), mail is 109sent to the user so named. If 110.Ev MAILTO 111is defined but empty (MAILTO=""), no 112mail will be sent. Otherwise mail is sent to the owner of the crontab. This 113option is useful if you decide on 114.Pa /bin/mail 115instead of 116.Pa /usr/lib/sendmail 117as 118your mailer when you install cron -- 119.Pa /bin/mail 120doesn't do aliasing, and UUCP 121usually doesn't read its mail. 122.Pp 123The format of a cron command is very much the V7 standard, with a number of 124upward-compatible extensions. Each line has five time and date fields, 125followed by a user name 126(with optional ``:<group>'' and ``/<login-class>'' suffixes) 127if this is the system crontab file, 128followed by a command. Commands are executed by 129.Xr cron 8 130when the minute, hour, and month of year fields match the current time, 131.Em and 132when at least one of the two day fields (day of month, or day of week) 133matches the current time (see ``Note'' below). 134.Xr cron 8 135examines cron entries once every minute. 136The time and date fields are: 137.Bd -literal -offset indent 138field allowed values 139----- -------------- 140minute 0-59 141hour 0-23 142day of month 1-31 143month 1-12 (or names, see below) 144day of week 0-7 (0 or 7 is Sun, or use names) 145.Ed 146.Pp 147A field may be an asterisk (*), which always stands for ``first\-last''. 148.Pp 149Ranges of numbers are allowed. Ranges are two numbers separated 150with a hyphen. The specified range is inclusive. For example, 1518-11 for an ``hours'' entry specifies execution at hours 8, 9, 10 152and 11. 153.Pp 154Lists are allowed. A list is a set of numbers (or ranges) 155separated by commas. Examples: ``1,2,5,9'', ``0-4,8-12''. 156.Pp 157Step values can be used in conjunction with ranges. Following 158a range with ``/<number>'' specifies skips of the number's value 159through the range. For example, ``0-23/2'' can be used in the hours 160field to specify command execution every other hour (the alternative 161in the V7 standard is ``0,2,4,6,8,10,12,14,16,18,20,22''). Steps are 162also permitted after an asterisk, so if you want to say ``every two 163hours'', just use ``*/2''. 164.Pp 165Names can also be used for the ``month'' and ``day of week'' 166fields. Use the first three letters of the particular 167day or month (case doesn't matter). Ranges or 168lists of names are not allowed. 169.Pp 170The ``sixth'' field (the rest of the line) specifies the command to be 171run. 172The entire command portion of the line, up to a newline or % 173character, will be executed by 174.Pa /bin/sh 175or by the shell 176specified in the 177.Ev SHELL 178variable of the cronfile. 179Percent-signs (%) in the command, unless escaped with backslash 180(\\), will be changed into newline characters, and all data 181after the first % will be sent to the command as standard 182input. 183.Pp 184Note: The day of a command's execution can be specified by two 185fields \(em day of month, and day of week. If both fields are 186restricted (ie, aren't *), the command will be run when 187.Em either 188field matches the current time. For example, 189``30 4 1,15 * 5'' 190would cause a command to be run at 4:30 am on the 1st and 15th of each 191month, plus every Friday. 192.Pp 193Instead of the first five fields, 194one of eight special strings may appear: 195.Bd -literal -offset indent 196string meaning 197------ ------- 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 * * * *". 206.Ed 207.Sh EXAMPLE CRON FILE 208.Bd -literal 209 210# use /bin/sh to run commands, overriding the default set by cron 211SHELL=/bin/sh 212# mail any output to `paul', no matter whose crontab this is 213MAILTO=paul 214# 215# run five minutes after midnight, every day 2165 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 21815 14 1 * * $HOME/bin/monthly 219# run at 10 pm on weekdays, annoy Joe 2200 22 * * 1-5 mail -s "It's 10pm" joe%Joe,%%Where are your kids?% 22123 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday" 2225 4 * * sun echo "run at 5 after 4 every sunday" 223.Ed 224.Sh SEE ALSO 225.Xr crontab 1 , 226.Xr cron 8 227.Sh EXTENSIONS 228When specifying day of week, both day 0 and day 7 will be considered Sunday. 229.Bx 230and 231.Tn ATT 232seem to disagree about this. 233.Pp 234Lists and ranges are allowed to co-exist in the same field. "1-3,7-9" would 235be rejected by 236.Tn ATT 237or 238.Bx 239cron -- they want to see "1-3" or "7,8,9" ONLY. 240.Pp 241Ranges can include "steps", so "1-9/2" is the same as "1,3,5,7,9". 242.Pp 243Names of months or days of the week can be specified by name. 244.Pp 245Environment variables can be set in the crontab. In 246.Bx 247or 248.Tn ATT , 249the 250environment handed to child processes is basically the one from 251.Pa /etc/rc . 252.Pp 253Command output is mailed to the crontab owner 254.No ( Bx 255can't do this), can be 256mailed to a person other than the crontab owner (SysV can't do this), or the 257feature can be turned off and no mail will be sent at all (SysV can't do this 258either). 259.Pp 260All of the 261.Sq @ 262commands that can appear in place of the first five fields 263are extensions. 264.Sh AUTHORS 265.An Paul Vixie Aq paul@vix.com 266.Sh BUGS 267If you're in one of the 70-odd countries that observe Daylight 268Savings Time, jobs scheduled during the rollback or advance will be 269affected. In general, it's not a good idea to schedule jobs during 270this period. 271.Pp 272For US timezones (except parts of IN, AZ, and HI) the time shift occurs at 2732AM local time. For others, the output of the 274.Xr zdump 8 275program's verbose 276.Fl ( v ) 277option can be used to determine the moment of time shift. 278