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.\" $Id: crontab.5,v 1.7 1997/11/02 17:22:10 ache 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.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. 58.Pp 59Several environment variables are set up 60automatically by the 61.Xr cron 8 62daemon. 63.Ev SHELL 64is set to 65.Pa /bin/sh , 66and 67.Ev LOGNAME 68and 69.Ev HOME 70are set from the 71.Pa /etc/passwd 72line of the crontab's owner. 73.Ev HOME 74and 75.Ev SHELL 76may be overridden by settings in the crontab; 77.Ev LOGNAME 78may not. 79.Pp 80(Another note: the 81.Ev LOGNAME 82variable is sometimes called 83.Ev USER 84on BSD systems... 85on these systems, 86.Ev USER 87will be set also). 88.Pp 89In addition to 90.Ev LOGNAME , 91.Ev HOME , 92and 93.Ev SHELL , 94.Xr cron 8 95will look at 96.Ev MAILTO 97if it has any reason to send mail as a result of running 98commands in ``this'' crontab. If 99.Ev MAILTO 100is defined (and non-empty), mail is 101sent to the user so named. If 102.Ev MAILTO 103is defined but empty (MAILTO=""), no 104mail will be sent. Otherwise mail is sent to the owner of the crontab. This 105option is useful if you decide on 106.Pa /bin/mail 107instead of 108.Pa /usr/lib/sendmail 109as 110your mailer when you install cron -- 111.Pa /bin/mail 112doesn't do aliasing, and UUCP 113usually doesn't read its mail. 114.Pp 115The format of a cron command is very much the V7 standard, with a number of 116upward-compatible extensions. Each line has five time and date fields, 117followed by a user name 118(with optional ``:<group>'' and ``/<login-class>'' suffixes) 119if this is the system crontab file, 120followed by a command. Commands are executed by 121.Xr cron 8 122when the minute, hour, and month of year fields match the current time, 123.Em and 124when at least one of the two day fields (day of month, or day of week) 125match the current time (see ``Note'' below). 126.Xr cron 8 127examines cron entries once every minute. 128The time and date fields are: 129.Bd -literal -offset indent 130field allowed values 131----- -------------- 132minute 0-59 133hour 0-23 134day of month 1-31 135month 1-12 (or names, see below) 136day of week 0-7 (0 or 7 is Sun, or use names) 137.Ed 138.Pp 139A field may be an asterisk (*), which always stands for ``first\-last''. 140.Pp 141Ranges of numbers are allowed. Ranges are two numbers separated 142with a hyphen. The specified range is inclusive. For example, 1438-11 for an ``hours'' entry specifies execution at hours 8, 9, 10 144and 11. 145.Pp 146Lists are allowed. A list is a set of numbers (or ranges) 147separated by commas. Examples: ``1,2,5,9'', ``0-4,8-12''. 148.Pp 149Step values can be used in conjunction with ranges. Following 150a range with ``/<number>'' specifies skips of the number's value 151through the range. For example, ``0-23/2'' can be used in the hours 152field to specify command execution every other hour (the alternative 153in the V7 standard is ``0,2,4,6,8,10,12,14,16,18,20,22''). Steps are 154also permitted after an asterisk, so if you want to say ``every two 155hours'', just use ``*/2''. 156.Pp 157Names can also be used for the ``month'' and ``day of week'' 158fields. Use the first three letters of the particular 159day or month (case doesn't matter). Ranges or 160lists of names are not allowed. 161.Pp 162The ``sixth'' field (the rest of the line) specifies the command to be 163run. 164The entire command portion of the line, up to a newline or % 165character, will be executed by 166.Pa /bin/sh 167or by the shell 168specified in the 169.Ev SHELL 170variable of the cronfile. 171Percent-signs (%) in the command, unless escaped with backslash 172(\\), will be changed into newline characters, and all data 173after the first % will be sent to the command as standard 174input. 175.Pp 176Note: The day of a command's execution can be specified by two 177fields \(em day of month, and day of week. If both fields are 178restricted (ie, aren't *), the command will be run when 179.Em either 180field matches the current time. For example, 181.br 182``30 4 1,15 * 5'' 183would cause a command to be run at 4:30 am on the 1st and 15th of each 184month, plus every Friday. 185.Sh EXAMPLE CRON FILE 186.Bd -literal 187 188# use /bin/sh to run commands, no matter what /etc/passwd says 189SHELL=/bin/sh 190# mail any output to `paul', no matter whose crontab this is 191MAILTO=paul 192# 193# run five minutes after midnight, every day 1945 0 * * * $HOME/bin/daily.job >> $HOME/tmp/out 2>&1 195# run at 2:15pm on the first of every month -- output mailed to paul 19615 14 1 * * $HOME/bin/monthly 197# run at 10 pm on weekdays, annoy Joe 1980 22 * * 1-5 mail -s "It's 10pm" joe%Joe,%%Where are your kids?% 19923 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday" 2005 4 * * sun echo "run at 5 after 4 every sunday" 201.Ed 202.Sh SEE ALSO 203.Xr crontab 1 , 204.Xr cron 8 205.Sh EXTENSIONS 206When specifying day of week, both day 0 and day 7 will be considered Sunday. 207BSD and ATT seem to disagree about this. 208.Pp 209Lists and ranges are allowed to co-exist in the same field. "1-3,7-9" would 210be rejected by ATT or BSD cron -- they want to see "1-3" or "7,8,9" ONLY. 211.Pp 212Ranges can include "steps", so "1-9/2" is the same as "1,3,5,7,9". 213.Pp 214Names of months or days of the week can be specified by name. 215.Pp 216Environment variables can be set in the crontab. In BSD or ATT, the 217environment handed to child processes is basically the one from 218.Pa /etc/rc . 219.Pp 220Command output is mailed to the crontab owner (BSD can't do this), can be 221mailed to a person other than the crontab owner (SysV can't do this), or the 222feature can be turned off and no mail will be sent at all (SysV can't do this 223either). 224.Sh AUTHORS 225.An Paul Vixie Aq paul@vix.com 226