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, 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. 109.Ev MAILTO 110may also be used to direct mail to multiple recipients 111by seperating recipient users with a comma. 112If 113.Ev MAILTO 114is defined but empty (MAILTO=""), no 115mail will be sent. Otherwise mail is sent to the owner of the crontab. This 116option is useful if you decide on 117.Pa /bin/mail 118instead of 119.Pa /usr/lib/sendmail 120as 121your mailer when you install cron -- 122.Pa /bin/mail 123doesn't do aliasing, and UUCP 124usually doesn't read its mail. 125.Pp 126The format of a cron command is very much the V7 standard, with a number of 127upward-compatible extensions. Each line has five time and date fields, 128followed by a user name 129(with optional ``:<group>'' and ``/<login-class>'' suffixes) 130if this is the system crontab file, 131followed by a command. Commands are executed by 132.Xr cron 8 133when the minute, hour, and month of year fields match the current time, 134.Em and 135when at least one of the two day fields (day of month, or day of week) 136matches the current time (see ``Note'' below). 137.Xr cron 8 138examines cron entries once every minute. 139The time and date fields are: 140.Bd -literal -offset indent 141field allowed values 142----- -------------- 143minute 0-59 144hour 0-23 145day of month 1-31 146month 1-12 (or names, see below) 147day of week 0-7 (0 or 7 is Sun, or use names) 148.Ed 149.Pp 150A field may be an asterisk (*), which always stands for ``first\-last''. 151.Pp 152Ranges of numbers are allowed. Ranges are two numbers separated 153with a hyphen. The specified range is inclusive. For example, 1548-11 for an ``hours'' entry specifies execution at hours 8, 9, 10 155and 11. 156.Pp 157Lists are allowed. A list is a set of numbers (or ranges) 158separated by commas. Examples: ``1,2,5,9'', ``0-4,8-12''. 159.Pp 160Step values can be used in conjunction with ranges. Following 161a range with ``/<number>'' specifies skips of the number's value 162through the range. For example, ``0-23/2'' can be used in the hours 163field to specify command execution every other hour (the alternative 164in the V7 standard is ``0,2,4,6,8,10,12,14,16,18,20,22''). Steps are 165also permitted after an asterisk, so if you want to say ``every two 166hours'', just use ``*/2''. 167.Pp 168Names can also be used for the ``month'' and ``day of week'' 169fields. Use the first three letters of the particular 170day or month (case doesn't matter). Ranges or 171lists of names are not allowed. 172.Pp 173The ``sixth'' field (the rest of the line) specifies the command to be 174run. 175The entire command portion of the line, up to a newline or % 176character, will be executed by 177.Pa /bin/sh 178or by the shell 179specified in the 180.Ev SHELL 181variable of the cronfile. 182Percent-signs (%) in the command, unless escaped with backslash 183(\\), will be changed into newline characters, and all data 184after the first % will be sent to the command as standard 185input. 186.Pp 187Note: The day of a command's execution can be specified by two 188fields \(em day of month, and day of week. If both fields are 189restricted (ie, aren't *), the command will be run when 190.Em either 191field matches the current time. For example, 192``30 4 1,15 * 5'' 193would cause a command to be run at 4:30 am on the 1st and 15th of each 194month, plus every Friday. 195.Pp 196Instead of the first five fields, 197one of eight special strings may appear: 198.Bd -literal -offset indent 199string meaning 200------ ------- 201@reboot Run once, at startup. 202@yearly Run once a year, "0 0 1 1 *". 203@annually (same as @yearly) 204@monthly Run once a month, "0 0 1 * *". 205@weekly Run once a week, "0 0 * * 0". 206@daily Run once a day, "0 0 * * *". 207@midnight (same as @daily) 208@hourly Run once an hour, "0 * * * *". 209.Ed 210.Sh EXAMPLE CRON FILE 211.Bd -literal 212 213# use /bin/sh to run commands, overriding the default set by cron 214SHELL=/bin/sh 215# mail any output to `paul', no matter whose crontab this is 216MAILTO=paul 217# 218# run five minutes after midnight, every day 2195 0 * * * $HOME/bin/daily.job >> $HOME/tmp/out 2>&1 220# run at 2:15pm on the first of every month -- output mailed to paul 22115 14 1 * * $HOME/bin/monthly 222# run at 10 pm on weekdays, annoy Joe 2230 22 * * 1-5 mail -s "It's 10pm" joe%Joe,%%Where are your kids?% 22423 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday" 2255 4 * * sun echo "run at 5 after 4 every sunday" 226.Ed 227.Sh SEE ALSO 228.Xr crontab 1 , 229.Xr cron 8 230.Sh EXTENSIONS 231When specifying day of week, both day 0 and day 7 will be considered Sunday. 232.Bx 233and 234.Tn ATT 235seem to disagree about this. 236.Pp 237Lists and ranges are allowed to co-exist in the same field. "1-3,7-9" would 238be rejected by 239.Tn ATT 240or 241.Bx 242cron -- they want to see "1-3" or "7,8,9" ONLY. 243.Pp 244Ranges can include "steps", so "1-9/2" is the same as "1,3,5,7,9". 245.Pp 246Names of months or days of the week can be specified by name. 247.Pp 248Environment variables can be set in the crontab. In 249.Bx 250or 251.Tn ATT , 252the 253environment handed to child processes is basically the one from 254.Pa /etc/rc . 255.Pp 256Command output is mailed to the crontab owner 257.No ( Bx 258can't do this), can be 259mailed to a person other than the crontab owner (SysV can't do this), or the 260feature can be turned off and no mail will be sent at all (SysV can't do this 261either). 262.Pp 263All of the 264.Sq @ 265commands that can appear in place of the first five fields 266are extensions. 267.Sh AUTHORS 268.An Paul Vixie Aq paul@vix.com 269.Sh BUGS 270If you're in one of the 70-odd countries that observe Daylight 271Savings Time, jobs scheduled during the rollback or advance will be 272affected. In general, it's not a good idea to schedule jobs during 273this period. 274.Pp 275For US timezones (except parts of IN, AZ, and HI) the time shift occurs at 2762AM local time. For others, the output of the 277.Xr zdump 8 278program's verbose 279.Fl ( v ) 280option can be used to determine the moment of time shift. 281