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.\" 20.Dd January 24, 1994 21.Dt CRONTAB 5 22.Os 23.Sh NAME 24.Nm crontab 25.Nd tables for driving cron 26.Sh DESCRIPTION 27A 28.Nm 29file contains instructions to the 30.Xr cron 8 31daemon of the general form: ``run this command at this time on this date''. 32Each user has their own crontab, and commands in any given crontab will be 33executed as the user who owns the crontab. Uucp and News will usually have 34their own crontabs, eliminating the need for explicitly running 35.Xr su 1 36as part of a cron command. 37.Pp 38Blank lines and leading spaces and tabs are ignored. Lines whose first 39non-space character is a pound-sign (#) are comments, and are ignored. 40Note that comments are not allowed on the same line as cron commands, since 41they will be taken to be part of the command. Similarly, comments are not 42allowed on the same line as environment variable settings. 43.Pp 44An active line in a crontab will be either an environment setting or a cron 45command. An environment setting is of the form, 46.Bd -literal 47 name = value 48.Ed 49.Pp 50where the spaces around the equal-sign (=) are optional, and any subsequent 51non-leading spaces in 52.Em value 53will be part of the value assigned to 54.Em name . 55The 56.Em value 57string may be placed in quotes (single or double, but matching) to preserve 58leading or trailing blanks. 59The 60.Em name 61string may also be placed in quote (single or double, but matching) 62to preserve leading, trailing or inner blanks. 63.Pp 64Several environment variables are set up 65automatically by the 66.Xr cron 8 67daemon. 68.Ev SHELL 69is set to 70.Pa /bin/sh , 71and 72.Ev LOGNAME 73and 74.Ev HOME 75are set from the 76.Pa /etc/passwd 77line of the crontab's owner. 78.Ev HOME 79and 80.Ev SHELL 81may be overridden by settings in the crontab; 82.Ev LOGNAME 83may not. 84.Pp 85(Another note: the 86.Ev LOGNAME 87variable is sometimes called 88.Ev USER 89on 90.Bx 91systems... 92On these systems, 93.Ev USER 94will be set also). 95.Pp 96In addition to 97.Ev LOGNAME , 98.Ev HOME , 99and 100.Ev SHELL , 101.Xr cron 8 102will look at 103.Ev MAILTO 104if it has any reason to send mail as a result of running 105commands in ``this'' crontab. If 106.Ev MAILTO 107is defined (and non-empty), mail is 108sent to the user so named. If 109.Ev MAILTO 110is defined but empty (MAILTO=""), no 111mail will be sent. Otherwise mail is sent to the owner of the crontab. This 112option is useful if you decide on 113.Pa /bin/mail 114instead of 115.Pa /usr/lib/sendmail 116as 117your mailer when you install cron -- 118.Pa /bin/mail 119doesn't do aliasing, and UUCP 120usually doesn't read its mail. 121.Pp 122The format of a cron command is very much the V7 standard, with a number of 123upward-compatible extensions. Each line has five time and date fields, 124followed by a user name 125(with optional ``:<group>'' and ``/<login-class>'' suffixes) 126if this is the system crontab file, 127followed by a command. Commands are executed by 128.Xr cron 8 129when the minute, hour, and month of year fields match the current time, 130.Em and 131when at least one of the two day fields (day of month, or day of week) 132matches the current time (see ``Note'' below). 133.Xr cron 8 134examines cron entries once every minute. 135The time and date fields are: 136.Bd -literal -offset indent 137field allowed values 138----- -------------- 139minute 0-59 140hour 0-23 141day of month 1-31 142month 1-12 (or names, see below) 143day of week 0-7 (0 or 7 is Sun, or use names) 144.Ed 145.Pp 146A field may be an asterisk (*), which always stands for ``first\-last''. 147.Pp 148Ranges of numbers are allowed. Ranges are two numbers separated 149with a hyphen. The specified range is inclusive. For example, 1508-11 for an ``hours'' entry specifies execution at hours 8, 9, 10 151and 11. 152.Pp 153Lists are allowed. A list is a set of numbers (or ranges) 154separated by commas. Examples: ``1,2,5,9'', ``0-4,8-12''. 155.Pp 156Step values can be used in conjunction with ranges. Following 157a range with ``/<number>'' specifies skips of the number's value 158through the range. For example, ``0-23/2'' can be used in the hours 159field to specify command execution every other hour (the alternative 160in the V7 standard is ``0,2,4,6,8,10,12,14,16,18,20,22''). Steps are 161also permitted after an asterisk, so if you want to say ``every two 162hours'', just use ``*/2''. 163.Pp 164Names can also be used for the ``month'' and ``day of week'' 165fields. Use the first three letters of the particular 166day or month (case doesn't matter). Ranges or 167lists of names are not allowed. 168.Pp 169The ``sixth'' field (the rest of the line) specifies the command to be 170run. 171The entire command portion of the line, up to a newline or % 172character, will be executed by 173.Pa /bin/sh 174or by the shell 175specified in the 176.Ev SHELL 177variable of the cronfile. 178Percent-signs (%) in the command, unless escaped with backslash 179(\\), will be changed into newline characters, and all data 180after the first % will be sent to the command as standard 181input. 182.Pp 183Note: The day of a command's execution can be specified by two 184fields \(em day of month, and day of week. If both fields are 185restricted (ie, aren't *), the command will be run when 186.Em either 187field matches the current time. For example, 188``30 4 1,15 * 5'' 189would cause a command to be run at 4:30 am on the 1st and 15th of each 190month, plus every Friday. 191.Pp 192Instead of the first five fields, 193one of eight special strings may appear: 194.Bd -literal -offset indent 195string meaning 196------ ------- 197@reboot Run once, at startup. 198@yearly Run once a year, "0 0 1 1 *". 199@annually (same as @yearly) 200@monthly Run once a month, "0 0 1 * *". 201@weekly Run once a week, "0 0 * * 0". 202@daily Run once a day, "0 0 * * *". 203@midnight (same as @daily) 204@hourly Run once an hour, "0 * * * *". 205.Ed 206.Sh EXAMPLE CRON FILE 207.Bd -literal 208 209# use /bin/sh to run commands, overriding the default set by cron 210SHELL=/bin/sh 211# mail any output to `paul', no matter whose crontab this is 212MAILTO=paul 213# 214# run five minutes after midnight, every day 2155 0 * * * $HOME/bin/daily.job >> $HOME/tmp/out 2>&1 216# run at 2:15pm on the first of every month -- output mailed to paul 21715 14 1 * * $HOME/bin/monthly 218# run at 10 pm on weekdays, annoy Joe 2190 22 * * 1-5 mail -s "It's 10pm" joe%Joe,%%Where are your kids?% 22023 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday" 2215 4 * * sun echo "run at 5 after 4 every sunday" 222.Ed 223.Sh SEE ALSO 224.Xr crontab 1 , 225.Xr cron 8 226.Sh EXTENSIONS 227When specifying day of week, both day 0 and day 7 will be considered Sunday. 228.Bx 229and 230.Tn ATT 231seem to disagree about this. 232.Pp 233Lists and ranges are allowed to co-exist in the same field. "1-3,7-9" would 234be rejected by 235.Tn ATT 236or 237.Bx 238cron -- they want to see "1-3" or "7,8,9" ONLY. 239.Pp 240Ranges can include "steps", so "1-9/2" is the same as "1,3,5,7,9". 241.Pp 242Names of months or days of the week can be specified by name. 243.Pp 244Environment variables can be set in the crontab. In 245.Bx 246or 247.Tn ATT , 248the 249environment handed to child processes is basically the one from 250.Pa /etc/rc . 251.Pp 252Command output is mailed to the crontab owner 253.No ( Bx 254can't do this), can be 255mailed to a person other than the crontab owner (SysV can't do this), or the 256feature can be turned off and no mail will be sent at all (SysV can't do this 257either). 258.Pp 259All of the 260.Sq @ 261commands that can appear in place of the first five fields 262are extensions. 263.Sh AUTHORS 264.An Paul Vixie Aq Mt paul@vix.com 265.Sh BUGS 266If you're in one of the 70-odd countries that observe Daylight 267Savings Time, jobs scheduled during the rollback or advance will be 268affected. In general, it's not a good idea to schedule jobs during 269this period. 270.Pp 271For US timezones (except parts of IN, AZ, and HI) the time shift occurs at 2722AM local time. For others, the output of the 273.Xr zdump 8 274program's verbose 275.Fl ( v ) 276option can be used to determine the moment of time shift. 277