54a3fb7337
well, expect our two seperate directories for cron and crontab to go away shortly. Submitted by: jkh
189 lines
7.1 KiB
Groff
189 lines
7.1 KiB
Groff
.\"/* Copyright 1988,1990,1993,1994 by Paul Vixie
|
|
.\" * All rights reserved
|
|
.\" *
|
|
.\" * Distribute freely, except: don't remove my name from the source or
|
|
.\" * documentation (don't take credit for my work), mark your changes (don't
|
|
.\" * get me blamed for your possible bugs), don't alter or remove this
|
|
.\" * notice. May be sold if buildable source is provided to buyer. No
|
|
.\" * warrantee of any kind, express or implied, is included with this
|
|
.\" * software; use at your own risk, responsibility for damages (if any) to
|
|
.\" * anyone resulting from the use of this software rests entirely with the
|
|
.\" * user.
|
|
.\" *
|
|
.\" * Send bug reports, bug fixes, enhancements, requests, flames, etc., and
|
|
.\" * I'll try to keep a version up to date. I can be reached as follows:
|
|
.\" * Paul Vixie <paul@vix.com> uunet!decwrl!vixie!paul
|
|
.\" */
|
|
.\"
|
|
.\" $Id: crontab.5,v 2.4 1994/01/15 20:43:43 vixie Exp $
|
|
.\"
|
|
.TH CRONTAB 5 "24 January 1994"
|
|
.UC 4
|
|
.SH NAME
|
|
crontab \- tables for driving cron
|
|
.SH DESCRIPTION
|
|
A
|
|
.I crontab
|
|
file contains instructions to the
|
|
.IR cron (8)
|
|
daemon of the general form: ``run this command at this time on this date''.
|
|
Each user has their own crontab, and commands in any given crontab will be
|
|
executed as the user who owns the crontab. Uucp and News will usually have
|
|
their own crontabs, eliminating the need for explicitly running
|
|
.IR su (1)
|
|
as part of a cron command.
|
|
.PP
|
|
Blank lines and leading spaces and tabs are ignored. Lines whose first
|
|
non-space character is a pound-sign (#) are comments, and are ignored.
|
|
Note that comments are not allowed on the same line as cron commands, since
|
|
they will be taken to be part of the command. Similarly, comments are not
|
|
allowed on the same line as environment variable settings.
|
|
.PP
|
|
An active line in a crontab will be either an environment setting or a cron
|
|
command. An environment setting is of the form,
|
|
.PP
|
|
name = value
|
|
.PP
|
|
where the spaces around the equal-sign (=) are optional, and any subsequent
|
|
non-leading spaces in
|
|
.I value
|
|
will be part of the value assigned to
|
|
.IR name .
|
|
The
|
|
.I value
|
|
string may be placed in quotes (single or double, but matching) to preserve
|
|
leading or trailing blanks.
|
|
.PP
|
|
Several environment variables are set up
|
|
automatically by the
|
|
.IR cron (8)
|
|
daemon.
|
|
SHELL is set to /bin/sh, and LOGNAME and HOME are set from the /etc/passwd
|
|
line of the crontab's owner.
|
|
HOME and SHELL may be overridden by settings in the crontab; LOGNAME may not.
|
|
.PP
|
|
(Another note: the LOGNAME variable is sometimes called USER on BSD systems...
|
|
on these systems, USER will be set also.)
|
|
.PP
|
|
In addition to LOGNAME, HOME, and SHELL,
|
|
.IR cron (8)
|
|
will look at MAILTO if it has any reason to send mail as a result of running
|
|
commands in ``this'' crontab. If MAILTO is defined (and non-empty), mail is
|
|
sent to the user so named. If MAILTO is defined but empty (MAILTO=""), no
|
|
mail will be sent. Otherwise mail is sent to the owner of the crontab. This
|
|
option is useful if you decide on /bin/mail instead of /usr/lib/sendmail as
|
|
your mailer when you install cron -- /bin/mail doesn't do aliasing, and UUCP
|
|
usually doesn't read its mail.
|
|
.PP
|
|
The format of a cron command is very much the V7 standard, with a number of
|
|
upward-compatible extensions. Each line has five time and date fields,
|
|
followed by a user name if this is the system crontab file,
|
|
followed by a command. Commands are executed by
|
|
.IR cron (8)
|
|
when the minute, hour, and month of year fields match the current time,
|
|
.I and
|
|
when at least one of the two day fields (day of month, or day of week)
|
|
match the current time (see ``Note'' below).
|
|
.IR cron (8)
|
|
examines cron entries once every minute.
|
|
The time and date fields are:
|
|
.IP
|
|
.ta 1.5i
|
|
field allowed values
|
|
.br
|
|
----- --------------
|
|
.br
|
|
minute 0-59
|
|
.br
|
|
hour 0-23
|
|
.br
|
|
day of month 0-31
|
|
.br
|
|
month 0-12 (or names, see below)
|
|
.br
|
|
day of week 0-7 (0 or 7 is Sun, or use names)
|
|
.br
|
|
.PP
|
|
A field may be an asterisk (*), which always stands for ``first\-last''.
|
|
.PP
|
|
Ranges of numbers are allowed. Ranges are two numbers separated
|
|
with a hyphen. The specified range is inclusive. For example,
|
|
8-11 for an ``hours'' entry specifies execution at hours 8, 9, 10
|
|
and 11.
|
|
.PP
|
|
Lists are allowed. A list is a set of numbers (or ranges)
|
|
separated by commas. Examples: ``1,2,5,9'', ``0-4,8-12''.
|
|
.PP
|
|
Step values can be used in conjunction with ranges. Following
|
|
a range with ``/<number>'' specifies skips of the number's value
|
|
through the range. For example, ``0-23/2'' can be used in the hours
|
|
field to specify command execution every other hour (the alternative
|
|
in the V7 standard is ``0,2,4,6,8,10,12,14,16,18,20,22''). Steps are
|
|
also permitted after an asterisk, so if you want to say ``every two
|
|
hours'', just use ``*/2''.
|
|
.PP
|
|
Names can also be used for the ``month'' and ``day of week''
|
|
fields. Use the first three letters of the particular
|
|
day or month (case doesn't matter). Ranges or
|
|
lists of names are not allowed.
|
|
.PP
|
|
The ``sixth'' field (the rest of the line) specifies the command to be
|
|
run.
|
|
The entire command portion of the line, up to a newline or %
|
|
character, will be executed by /bin/sh or by the shell
|
|
specified in the SHELL variable of the cronfile.
|
|
Percent-signs (%) in the command, unless escaped with backslash
|
|
(\\), will be changed into newline characters, and all data
|
|
after the first % will be sent to the command as standard
|
|
input.
|
|
.PP
|
|
Note: The day of a command's execution can be specified by two
|
|
fields \(em day of month, and day of week. If both fields are
|
|
restricted (ie, aren't *), the command will be run when
|
|
.I either
|
|
field matches the current time. For example,
|
|
.br
|
|
``30 4 1,15 * 5''
|
|
would cause a command to be run at 4:30 am on the 1st and 15th of each
|
|
month, plus every Friday.
|
|
.SH EXAMPLE CRON FILE
|
|
.nf
|
|
|
|
# use /bin/sh to run commands, no matter what /etc/passwd says
|
|
SHELL=/bin/sh
|
|
# mail any output to `paul', no matter whose crontab this is
|
|
MAILTO=paul
|
|
#
|
|
# run five minutes after midnight, every day
|
|
5 0 * * * $HOME/bin/daily.job >> $HOME/tmp/out 2>&1
|
|
# run at 2:15pm on the first of every month -- output mailed to paul
|
|
15 14 1 * * $HOME/bin/monthly
|
|
# run at 10 pm on weekdays, annoy Joe
|
|
0 22 * * 1-5 mail -s "It's 10pm" joe%Joe,%%Where are your kids?%
|
|
23 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday"
|
|
5 4 * * sun echo "run at 5 after 4 every sunday"
|
|
.fi
|
|
.SH SEE ALSO
|
|
cron(8), crontab(1)
|
|
.SH EXTENSIONS
|
|
When specifying day of week, both day 0 and day 7 will be considered Sunday.
|
|
BSD and ATT seem to disagree about this.
|
|
.PP
|
|
Lists and ranges are allowed to co-exist in the same field. "1-3,7-9" would
|
|
be rejected by ATT or BSD cron -- they want to see "1-3" or "7,8,9" ONLY.
|
|
.PP
|
|
Ranges can include "steps", so "1-9/2" is the same as "1,3,5,7,9".
|
|
.PP
|
|
Names of months or days of the week can be specified by name.
|
|
.PP
|
|
Environment variables can be set in the crontab. In BSD or ATT, the
|
|
environment handed to child processes is basically the one from /etc/rc.
|
|
.PP
|
|
Command output is mailed to the crontab owner (BSD can't do this), can be
|
|
mailed to a person other than the crontab owner (SysV can't do this), or the
|
|
feature can be turned off and no mail will be sent at all (SysV can't do this
|
|
either).
|
|
.SH AUTHOR
|
|
.nf
|
|
Paul Vixie <paul@vix.com>
|