1.\"/* Copyright 1988,1990,1993,1994 by Paul Vixie 2.\" * All rights reserved 3.\" */ 4.\" 5.\" Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 6.\" Copyright (c) 1997,2000 by Internet Software Consortium, Inc. 7.\" 8.\" Permission to use, copy, modify, and distribute this software for any 9.\" purpose with or without fee is hereby granted, provided that the above 10.\" copyright notice and this permission notice appear in all copies. 11.\" 12.\" THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 13.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 14.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 15.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 16.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 17.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 18.\" OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 19.\" 20.\" $OpenBSD: crontab.5,v 1.37 2020/01/06 19:44:09 job Exp $ 21.\" 22.Dd $Mdocdate: January 6 2020 $ 23.Dt CRONTAB 5 24.Os 25.Sh NAME 26.Nm crontab 27.Nd tables for driving cron 28.Sh DESCRIPTION 29A 30.Nm 31file contains instructions to the 32.Xr cron 8 33daemon of the general form: 34.Dq at these times on these dates run this command . 35There may be a system 36.Nm 37and each user may have their own 38.Nm . 39Commands in any given 40.Nm 41will be 42executed either as the user who owns the 43.Nm 44or, in the case of the system 45.Nm crontab , 46as the user specified on the command line. 47.Pp 48While a 49.Nm 50is a text file, it is not intended to be directly edited. 51Creation, modification, and removal of a 52.Nm 53should be done using 54.Xr crontab 1 . 55.Pp 56Blank lines, leading spaces, and tabs are ignored. 57Lines whose first non-space character is a pound sign 58.Pq Ql # 59are comments, and are ignored. 60Note that comments are not allowed on the same line as 61.Xr cron 8 62commands, since 63they will be taken to be part of the command. 64Similarly, comments are not 65allowed on the same line as environment variable settings. 66.Pp 67An active line in a 68.Nm 69is either an environment variable setting or a 70.Xr cron 8 71command. 72.Pp 73Environment variable settings create the environment 74any command in the 75.Nm 76is run in. 77An environment variable setting is of the form: 78.Pp 79.Dl name = value 80.Pp 81The spaces around the equal sign 82.Pq Ql = 83are optional, and any subsequent non-leading spaces in 84.Ar value 85will be part of the value assigned to 86.Ar name . 87The 88.Ar value 89string may be placed in quotes 90.Pq single or double , but matching 91to preserve leading or trailing blanks. 92.Pp 93Lines in the system 94.Nm 95have six fixed fields plus a command, in the form: 96.Bd -ragged -offset indent 97.Ar minute 98.Ar hour 99.Ar day-of-month 100.Ar month 101.Ar day-of-week 102.Ar user 103.Ar command 104.Ed 105.Pp 106While lines in a user 107.Nm 108have five fixed fields plus a command, in the form: 109.Bd -ragged -offset indent 110.Ar minute 111.Ar hour 112.Ar day-of-month 113.Ar month 114.Ar day-of-week 115.Ar command 116.Ed 117.Pp 118Fields are separated by blanks or tabs. 119The command may be one or more fields long. 120The allowed values for the fields are: 121.Bl -column "day-of-month" "allowed values" -offset indent 122.It Sy field Ta Sy allowed values 123.It Ar minute Ta * or 0\(en59 124.It Ar hour Ta * or 0\(en23 125.It Ar day-of-month Ta * or 1\(en31 126.It Ar month Ta * or 1\(en12 or a name (see below) 127.It Ar day-of-week Ta * or 0\(en7 or a name (0 or 7 is Sunday) 128.It Ar user Ta a valid username 129.It Ar command Ta text 130.El 131.Pp 132Lists are allowed. 133A list is a set of numbers (or ranges) separated by commas. 134For example, 135.Dq 1,2,5,9 136or 137.Dq 0\(en4,8\(en12 . 138.Pp 139Ranges of numbers are allowed. 140Ranges are two numbers separated with a hyphen. 141The specified range is inclusive. 142For example, 1438\(en11 for an 144.Ar hour 145entry specifies execution at hours 8, 9, 10 and 11. 146.Pp 147Step values can be used in conjunction with ranges. 148Following a range with 149.No / Ns Ar number 150specifies skips of 151.Ar number 152through the range. 153For example, 154.Dq 0\(en23/2 155can be used in the 156.Ar hour 157field to specify command execution every other hour. 158Steps are also permitted after an asterisk, so to say 159.Dq every two hours , 160just use 161.Dq */2 . 162.Pp 163An asterisk 164.Pq Ql * 165is short form for a range of all allowed values. 166.Pp 167Names can be used in the 168.Ar month 169and 170.Ar day-of-week 171fields. 172Use the first three letters of the particular 173day or month (case doesn't matter). 174Ranges or lists of names are not allowed. 175.Pp 176The 177.Ar command 178field (the rest of the line) is the command to be 179run. 180The entire command portion of the line, up to a newline or % 181character, will be executed by 182.Pa /bin/sh 183or by the shell 184specified in the 185.Ev SHELL 186variable of the 187.Nm crontab . 188Percent signs 189.Pq Ql % 190in the command, unless escaped with a backslash 191.Pq Ql \e , 192will be changed into newline characters, and all data 193after the first 194.Ql % 195will be sent to the command as standard input. 196.Pp 197Commands may be modified as follows: 198.Bl -tag -width Ds 199.It Fl n Ar command 200No mail is sent after a successful run. 201The execution output will only be mailed if the command exits with a non-zero 202exit code. 203The 204.Fl n 205option is an attempt to cure potentially copious volumes of mail coming from 206.Xr cron 8 . 207.It Fl q Ar command 208Execution will not be logged. 209.El 210.Pp 211Commands are executed by 212.Xr cron 8 213when the 214.Ar minute , 215.Ar hour , 216and 217.Ar month 218fields match the current time, 219.Em and 220when at least one of the two day fields 221.Po Ar day-of-month 222or 223.Ar day-of-week Pc , 224match the current time. 225.Pp 226Note: The day of a command's execution can be specified by two 227fields \(em 228.Ar day-of-month 229and 230.Ar day-of-week . 231If both fields are restricted (i.e. aren't *), 232the command will be run when 233.Em either 234field matches the current time. 235For example, 236.Pp 237.Dl 30 4 1,15 * 5 238.Pp 239would cause a command to be run at 4:30 am on the 1st and 15th of each 240month, plus every Friday. 241.Pp 242Instead of the first five fields, one of eight special strings may appear: 243.Bl -column "@midnight" "meaning" -offset indent 244.It Sy string Ta Sy meaning 245.It @reboot Ta Run once, at startup. 246.It @yearly Ta Run every January 1 (0 0 1 1 *). 247.It @annually Ta The same as @yearly. 248.It @monthly Ta Run the first day of every month (0 0 1 * *). 249.It @weekly Ta Run every Sunday (0 0 * * 0). 250.It @daily Ta Run every midnight (0 0 * * *). 251.It @midnight Ta The same as @daily. 252.It @hourly Ta Run every hour, on the hour (0 * * * *). 253.El 254.Sh ENVIRONMENT 255.Bl -tag -width "LOGNAMEXXX" 256.It Ev HOME 257Set from the user's 258.Pa /etc/passwd 259entry. 260May be overridden by settings in the 261.Nm . 262.It Ev LOGNAME 263Set from the user's 264.Pa /etc/passwd 265entry. 266May not be overridden by settings in the 267.Nm . 268.It Ev MAILTO 269If 270.Ev MAILTO 271is defined and non-empty, 272mail is sent to the user so named. 273If 274.Ev MAILTO 275is defined but empty 276.Pq Ev MAILTO = Qq , 277no mail will be sent. 278Otherwise mail is sent to the owner of the 279.Nm . 280This is useful for pseudo-users that lack an alias 281that would otherwise redirect the mail to a real person. 282.It Ev SHELL 283Set to 284.Pa /bin/sh . 285May be overridden by settings in the 286.Nm . 287.It Ev USER 288Set from the user's 289.Pa /etc/passwd 290entry. 291May not be overridden by settings in the 292.Nm . 293.El 294.Sh FILES 295.Bl -tag -width "/var/cron/tabs/<user>XXX" -compact 296.It Pa /etc/crontab 297System crontab. 298.It Pa /var/cron/tabs/ Ns Aq Ar user 299User crontab. 300.El 301.Sh EXAMPLES 302.Bd -literal 303# use /bin/sh to run commands, no matter what /etc/passwd says 304SHELL=/bin/sh 305# mail any output to `paul', no matter whose crontab this is 306MAILTO=paul 307# 308# run five minutes after midnight, every day 3095 0 * * * $HOME/bin/daily.job >> $HOME/tmp/out 2>&1 310 311# run at 2:15pm on the first of every month -- job output will be sent 312# to paul, but only if $HOME/bin/monthly exits with a non-zero exit code 31315 14 1 * * -n $HOME/bin/monthly 314 315# run at 10 pm on weekdays, annoy Joe 3160 22 * * 1-5 mail -s "It's 10pm" joe%Joe,%%Where are your kids?% 317 31823 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday" 319 3205 4 * * sun echo "run at 5 after 4 every sunday" 321.Ed 322.Sh SEE ALSO 323.Xr crontab 1 , 324.Xr cron 8 325.Sh STANDARDS 326The 327.Nm 328file format is compliant with the 329.St -p1003.1-2008 330specification. 331The behaviours described below are all extensions to that standard: 332.Bl -dash 333.It 334The 335.Ar day-of-week 336field may use 7 to represent Sunday. 337.It 338Ranges may include 339.Dq steps . 340.It 341Months or days of the week can be specified by name. 342.It 343Mailing after a successful run can be suppressed with 344.Fl n . 345.It 346Logging can be suppressed with 347.Ql -q . 348.It 349Environment variables can be set in a crontab. 350.It 351Command output can be mailed to a person other than the crontab 352owner, or the feature can be turned off and no mail will be sent 353at all. 354.It 355All of the 356.Ql @ 357commands that can appear in place of the first five fields. 358.El 359.Sh AUTHORS 360.Nm 361was written by 362.An Paul Vixie Aq Mt vixie@isc.org . 363