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 1.5 1997/09/15 06:39:14 charnier 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 if this is the system crontab file, 118followed by a command. Commands are executed by 119.Xr cron 8 120when the minute, hour, and month of year fields match the current time, 121.Em and 122when at least one of the two day fields (day of month, or day of week) 123match the current time (see ``Note'' below). 124.Xr cron 8 125examines cron entries once every minute. 126The time and date fields are: 127.Bd -literal -offset indent 128field allowed values 129----- -------------- 130minute 0-59 131hour 0-23 132day of month 1-31 133month 1-12 (or names, see below) 134day of week 0-7 (0 or 7 is Sun, or use names) 135.Ed 136.Pp 137A field may be an asterisk (*), which always stands for ``first\-last''. 138.Pp 139Ranges of numbers are allowed. Ranges are two numbers separated 140with a hyphen. The specified range is inclusive. For example, 1418-11 for an ``hours'' entry specifies execution at hours 8, 9, 10 142and 11. 143.Pp 144Lists are allowed. A list is a set of numbers (or ranges) 145separated by commas. Examples: ``1,2,5,9'', ``0-4,8-12''. 146.Pp 147Step values can be used in conjunction with ranges. Following 148a range with ``/<number>'' specifies skips of the number's value 149through the range. For example, ``0-23/2'' can be used in the hours 150field to specify command execution every other hour (the alternative 151in the V7 standard is ``0,2,4,6,8,10,12,14,16,18,20,22''). Steps are 152also permitted after an asterisk, so if you want to say ``every two 153hours'', just use ``*/2''. 154.Pp 155Names can also be used for the ``month'' and ``day of week'' 156fields. Use the first three letters of the particular 157day or month (case doesn't matter). Ranges or 158lists of names are not allowed. 159.Pp 160The ``sixth'' field (the rest of the line) specifies the command to be 161run. 162The entire command portion of the line, up to a newline or % 163character, will be executed by 164.Pa /bin/sh 165or by the shell 166specified in the 167.Ev SHELL 168variable of the cronfile. 169Percent-signs (%) in the command, unless escaped with backslash 170(\\), will be changed into newline characters, and all data 171after the first % will be sent to the command as standard 172input. 173.Pp 174Note: The day of a command's execution can be specified by two 175fields \(em day of month, and day of week. If both fields are 176restricted (ie, aren't *), the command will be run when 177.Em either 178field matches the current time. For example, 179.br 180``30 4 1,15 * 5'' 181would cause a command to be run at 4:30 am on the 1st and 15th of each 182month, plus every Friday. 183.Sh EXAMPLE CRON FILE 184.Bd -literal 185 186# use /bin/sh to run commands, no matter what /etc/passwd says 187SHELL=/bin/sh 188# mail any output to `paul', no matter whose crontab this is 189MAILTO=paul 190# 191# run five minutes after midnight, every day 1925 0 * * * $HOME/bin/daily.job >> $HOME/tmp/out 2>&1 193# run at 2:15pm on the first of every month -- output mailed to paul 19415 14 1 * * $HOME/bin/monthly 195# run at 10 pm on weekdays, annoy Joe 1960 22 * * 1-5 mail -s "It's 10pm" joe%Joe,%%Where are your kids?% 19723 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday" 1985 4 * * sun echo "run at 5 after 4 every sunday" 199.Ed 200.Sh SEE ALSO 201.Xr crontab 1 , 202.Xr cron 8 203.Sh EXTENSIONS 204When specifying day of week, both day 0 and day 7 will be considered Sunday. 205BSD and ATT seem to disagree about this. 206.Pp 207Lists and ranges are allowed to co-exist in the same field. "1-3,7-9" would 208be rejected by ATT or BSD cron -- they want to see "1-3" or "7,8,9" ONLY. 209.Pp 210Ranges can include "steps", so "1-9/2" is the same as "1,3,5,7,9". 211.Pp 212Names of months or days of the week can be specified by name. 213.Pp 214Environment variables can be set in the crontab. In BSD or ATT, the 215environment handed to child processes is basically the one from 216.Pa /etc/rc . 217.Pp 218Command output is mailed to the crontab owner (BSD can't do this), can be 219mailed to a person other than the crontab owner (SysV can't do this), or the 220feature can be turned off and no mail will be sent at all (SysV can't do this 221either). 222.Sh AUTHOR 223.An Paul Vixie Aq paul@vix.com 224