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.\" $FreeBSD$ 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.Pp 47 name = value 48.Pp 49where the spaces around the equal-sign (=) are optional, and any subsequent 50non-leading spaces in 51.Em value 52will be part of the value assigned to 53.Em name . 54The 55.Em value 56string may be placed in quotes (single or double, but matching) to preserve 57leading or trailing blanks. 58The 59.Em name 60string may also be placed in quote (single or double, but matching) 61to preserve leading, traling or inner blanks. 62.Pp 63Several environment variables are set up 64automatically by the 65.Xr cron 8 66daemon. 67.Ev SHELL 68is set to 69.Pa /bin/sh , 70and 71.Ev LOGNAME 72and 73.Ev HOME 74are set from the 75.Pa /etc/passwd 76line of the crontab's owner. 77.Ev HOME 78and 79.Ev SHELL 80may be overridden by settings in the crontab; 81.Ev LOGNAME 82may not. 83.Pp 84(Another note: the 85.Ev LOGNAME 86variable is sometimes called 87.Ev USER 88on BSD systems... 89on these systems, 90.Ev USER 91will be set also). 92.Pp 93In addition to 94.Ev LOGNAME , 95.Ev HOME , 96and 97.Ev SHELL , 98.Xr cron 8 99will look at 100.Ev MAILTO 101if it has any reason to send mail as a result of running 102commands in ``this'' crontab. If 103.Ev MAILTO 104is defined (and non-empty), mail is 105sent to the user so named. If 106.Ev MAILTO 107is defined but empty (MAILTO=""), no 108mail will be sent. Otherwise mail is sent to the owner of the crontab. This 109option is useful if you decide on 110.Pa /bin/mail 111instead of 112.Pa /usr/lib/sendmail 113as 114your mailer when you install cron -- 115.Pa /bin/mail 116doesn't do aliasing, and UUCP 117usually doesn't read its mail. 118.Pp 119The format of a cron command is very much the V7 standard, with a number of 120upward-compatible extensions. Each line has five time and date fields, 121followed by a user name 122(with optional ``:<group>'' and ``/<login-class>'' suffixes) 123if this is the system crontab file, 124followed by a command. Commands are executed by 125.Xr cron 8 126when the minute, hour, and month of year fields match the current time, 127.Em and 128when at least one of the two day fields (day of month, or day of week) 129match the current time (see ``Note'' below). 130.Xr cron 8 131examines cron entries once every minute. 132The time and date fields are: 133.Bd -literal -offset indent 134field allowed values 135----- -------------- 136minute 0-59 137hour 0-23 138day of month 1-31 139month 1-12 (or names, see below) 140day of week 0-7 (0 or 7 is Sun, or use names) 141.Ed 142.Pp 143A field may be an asterisk (*), which always stands for ``first\-last''. 144.Pp 145Ranges of numbers are allowed. Ranges are two numbers separated 146with a hyphen. The specified range is inclusive. For example, 1478-11 for an ``hours'' entry specifies execution at hours 8, 9, 10 148and 11. 149.Pp 150Lists are allowed. A list is a set of numbers (or ranges) 151separated by commas. Examples: ``1,2,5,9'', ``0-4,8-12''. 152.Pp 153Step values can be used in conjunction with ranges. Following 154a range with ``/<number>'' specifies skips of the number's value 155through the range. For example, ``0-23/2'' can be used in the hours 156field to specify command execution every other hour (the alternative 157in the V7 standard is ``0,2,4,6,8,10,12,14,16,18,20,22''). Steps are 158also permitted after an asterisk, so if you want to say ``every two 159hours'', just use ``*/2''. 160.Pp 161Names can also be used for the ``month'' and ``day of week'' 162fields. Use the first three letters of the particular 163day or month (case doesn't matter). Ranges or 164lists of names are not allowed. 165.Pp 166The ``sixth'' field (the rest of the line) specifies the command to be 167run. 168The entire command portion of the line, up to a newline or % 169character, will be executed by 170.Pa /bin/sh 171or by the shell 172specified in the 173.Ev SHELL 174variable of the cronfile. 175Percent-signs (%) in the command, unless escaped with backslash 176(\\), will be changed into newline characters, and all data 177after the first % will be sent to the command as standard 178input. 179.Pp 180Note: The day of a command's execution can be specified by two 181fields \(em day of month, and day of week. If both fields are 182restricted (ie, aren't *), the command will be run when 183.Em either 184field matches the current time. For example, 185``30 4 1,15 * 5'' 186would cause a command to be run at 4:30 am on the 1st and 15th of each 187month, plus every Friday. 188.Pp 189Instead of the first five fields, 190one of eight special strings may appear: 191.Bd -literal -offset indent 192string meaning 193------ ------- 194@reboot Run once, at startup. 195@yearly Run once a year, "0 0 1 1 *". 196@annually (sames as @yearly) 197@monthly Run once a month, "0 0 1 * *". 198@weekly Run once a week, "0 0 * * 0". 199@daily Run once a day, "0 0 * * *". 200@midnight (same as @daily) 201@hourly Run once an hour, "0 * * * *". 202.Ed 203.Sh EXAMPLE CRON FILE 204.Bd -literal 205 206# use /bin/sh to run commands, overriding the default set by cron 207SHELL=/bin/sh 208# mail any output to `paul', no matter whose crontab this is 209MAILTO=paul 210# 211# run five minutes after midnight, every day 2125 0 * * * $HOME/bin/daily.job >> $HOME/tmp/out 2>&1 213# run at 2:15pm on the first of every month -- output mailed to paul 21415 14 1 * * $HOME/bin/monthly 215# run at 10 pm on weekdays, annoy Joe 2160 22 * * 1-5 mail -s "It's 10pm" joe%Joe,%%Where are your kids?% 21723 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday" 2185 4 * * sun echo "run at 5 after 4 every sunday" 219.Ed 220.Sh SEE ALSO 221.Xr crontab 1 , 222.Xr cron 8 223.Sh EXTENSIONS 224When specifying day of week, both day 0 and day 7 will be considered Sunday. 225BSD and ATT seem to disagree about this. 226.Pp 227Lists and ranges are allowed to co-exist in the same field. "1-3,7-9" would 228be rejected by ATT or BSD cron -- they want to see "1-3" or "7,8,9" ONLY. 229.Pp 230Ranges can include "steps", so "1-9/2" is the same as "1,3,5,7,9". 231.Pp 232Names of months or days of the week can be specified by name. 233.Pp 234Environment variables can be set in the crontab. In BSD or ATT, the 235environment handed to child processes is basically the one from 236.Pa /etc/rc . 237.Pp 238Command output is mailed to the crontab owner (BSD can't do this), can be 239mailed to a person other than the crontab owner (SysV can't do this), or the 240feature can be turned off and no mail will be sent at all (SysV can't do this 241either). 242.Pp 243All of the 244.Sq @ 245commands that can appear in place of the first five fields 246are extensions. 247.Sh AUTHORS 248.An Paul Vixie Aq paul@vix.com 249.Sh BUGS 250If you're in one of the 70-odd countries that observe Daylight 251Savings Time, jobs scheduled during the rollback or advance will be 252affected. In general, it's not a good idea to schedule jobs during 253this period. 254.Pp 255For US timezones (except parts of IN, AZ, and HI) the time shift occurs at 2562AM local time. For others, the output of the 257.Xr zdump 8 258program's verbose 259.Fl ( v ) 260option can be used to determine the moment of time shift. 261