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.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, traling 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 BSD systems... 90on these systems, 91.Ev USER 92will be set also). 93.Pp 94In addition to 95.Ev LOGNAME , 96.Ev HOME , 97and 98.Ev SHELL , 99.Xr cron 8 100will look at 101.Ev MAILTO 102if it has any reason to send mail as a result of running 103commands in ``this'' crontab. If 104.Ev MAILTO 105is defined (and non-empty), mail is 106sent to the user so named. If 107.Ev MAILTO 108is defined but empty (MAILTO=""), no 109mail will be sent. Otherwise mail is sent to the owner of the crontab. This 110option is useful if you decide on 111.Pa /bin/mail 112instead of 113.Pa /usr/lib/sendmail 114as 115your mailer when you install cron -- 116.Pa /bin/mail 117doesn't do aliasing, and UUCP 118usually doesn't read its mail. 119.Pp 120The format of a cron command is very much the V7 standard, with a number of 121upward-compatible extensions. Each line has five time and date fields, 122followed by a user name 123(with optional ``:<group>'' and ``/<login-class>'' suffixes) 124if this is the system crontab file, 125followed by a command. Commands are executed by 126.Xr cron 8 127when the minute, hour, and month of year fields match the current time, 128.Em and 129when at least one of the two day fields (day of month, or day of week) 130match the current time (see ``Note'' below). 131.Xr cron 8 132examines cron entries once every minute. 133The time and date fields are: 134.Bd -literal -offset indent 135field allowed values 136----- -------------- 137minute 0-59 138hour 0-23 139day of month 1-31 140month 1-12 (or names, see below) 141day of week 0-7 (0 or 7 is Sun, or use names) 142.Ed 143.Pp 144A field may be an asterisk (*), which always stands for ``first\-last''. 145.Pp 146Ranges of numbers are allowed. Ranges are two numbers separated 147with a hyphen. The specified range is inclusive. For example, 1488-11 for an ``hours'' entry specifies execution at hours 8, 9, 10 149and 11. 150.Pp 151Lists are allowed. A list is a set of numbers (or ranges) 152separated by commas. Examples: ``1,2,5,9'', ``0-4,8-12''. 153.Pp 154Step values can be used in conjunction with ranges. Following 155a range with ``/<number>'' specifies skips of the number's value 156through the range. For example, ``0-23/2'' can be used in the hours 157field to specify command execution every other hour (the alternative 158in the V7 standard is ``0,2,4,6,8,10,12,14,16,18,20,22''). Steps are 159also permitted after an asterisk, so if you want to say ``every two 160hours'', just use ``*/2''. 161.Pp 162Names can also be used for the ``month'' and ``day of week'' 163fields. Use the first three letters of the particular 164day or month (case doesn't matter). Ranges or 165lists of names are not allowed. 166.Pp 167The ``sixth'' field (the rest of the line) specifies the command to be 168run. 169The entire command portion of the line, up to a newline or % 170character, will be executed by 171.Pa /bin/sh 172or by the shell 173specified in the 174.Ev SHELL 175variable of the cronfile. 176Percent-signs (%) in the command, unless escaped with backslash 177(\\), will be changed into newline characters, and all data 178after the first % will be sent to the command as standard 179input. 180.Pp 181Note: The day of a command's execution can be specified by two 182fields \(em day of month, and day of week. If both fields are 183restricted (ie, aren't *), the command will be run when 184.Em either 185field matches the current time. For example, 186``30 4 1,15 * 5'' 187would cause a command to be run at 4:30 am on the 1st and 15th of each 188month, plus every Friday. 189.Pp 190Instead of the first five fields, 191one of eight special strings may appear: 192.Bd -literal -offset indent 193string meaning 194------ ------- 195@reboot Run once, at startup. 196@yearly Run once a year, "0 0 1 1 *". 197@annually (sames as @yearly) 198@monthly Run once a month, "0 0 1 * *". 199@weekly Run once a week, "0 0 * * 0". 200@daily Run once a day, "0 0 * * *". 201@midnight (same as @daily) 202@hourly Run once an hour, "0 * * * *". 203.Ed 204.Sh EXAMPLE CRON FILE 205.Bd -literal 206 207# use /bin/sh to run commands, overriding the default set by cron 208SHELL=/bin/sh 209# mail any output to `paul', no matter whose crontab this is 210MAILTO=paul 211# 212# run five minutes after midnight, every day 2135 0 * * * $HOME/bin/daily.job >> $HOME/tmp/out 2>&1 214# run at 2:15pm on the first of every month -- output mailed to paul 21515 14 1 * * $HOME/bin/monthly 216# run at 10 pm on weekdays, annoy Joe 2170 22 * * 1-5 mail -s "It's 10pm" joe%Joe,%%Where are your kids?% 21823 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday" 2195 4 * * sun echo "run at 5 after 4 every sunday" 220.Ed 221.Sh SEE ALSO 222.Xr crontab 1 , 223.Xr cron 8 224.Sh EXTENSIONS 225When specifying day of week, both day 0 and day 7 will be considered Sunday. 226BSD and ATT seem to disagree about this. 227.Pp 228Lists and ranges are allowed to co-exist in the same field. "1-3,7-9" would 229be rejected by ATT or BSD cron -- they want to see "1-3" or "7,8,9" ONLY. 230.Pp 231Ranges can include "steps", so "1-9/2" is the same as "1,3,5,7,9". 232.Pp 233Names of months or days of the week can be specified by name. 234.Pp 235Environment variables can be set in the crontab. In BSD or ATT, the 236environment handed to child processes is basically the one from 237.Pa /etc/rc . 238.Pp 239Command output is mailed to the crontab owner (BSD can't do this), can be 240mailed to a person other than the crontab owner (SysV can't do this), or the 241feature can be turned off and no mail will be sent at all (SysV can't do this 242either). 243.Pp 244All of the 245.Sq @ 246commands that can appear in place of the first five fields 247are extensions. 248.Sh AUTHORS 249.An Paul Vixie Aq paul@vix.com 250.Sh BUGS 251If you're in one of the 70-odd countries that observe Daylight 252Savings Time, jobs scheduled during the rollback or advance will be 253affected. In general, it's not a good idea to schedule jobs during 254this period. 255.Pp 256For US timezones (except parts of IN, AZ, and HI) the time shift occurs at 2572AM local time. For others, the output of the 258.Xr zdump 8 259program's verbose 260.Fl ( v ) 261option can be used to determine the moment of time shift. 262