Replace with the OpenBSD man page. It removes some historical comparisons
that are not very useful (and trully if any they belong to a separate section instead of being interspersed in the document), and organizes and formats the information better.
This commit is contained in:
christos
parent
40b0fdad11
commit
4911152229
|
|
@ -1,25 +1,27 @@
|
|||
.\" $NetBSD: crontab.5,v 1.5 2014/03/18 18:20:36 riastradh Exp $
|
||||
.\" $NetBSD: crontab.5,v 1.6 2018/06/14 22:02:57 christos Exp $
|
||||
.\"
|
||||
.\"/* 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
|
||||
.\" Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
|
||||
.\" Copyright (c) 1997,2000 by Internet Software Consortium, Inc.
|
||||
.\"
|
||||
.Dd July 15, 2010
|
||||
.\" Permission to use, copy, modify, and distribute this software for any
|
||||
.\" purpose with or without fee is hereby granted, provided that the above
|
||||
.\" copyright notice and this permission notice appear in all copies.
|
||||
.\"
|
||||
.\" THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
|
||||
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
|
||||
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
|
||||
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
|
||||
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
|
||||
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
|
||||
.\" OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
|
||||
.\"
|
||||
.\" $OpenBSD: crontab.5,v 1.36 2018/06/13 13:27:37 jmc Exp $
|
||||
.\"
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.Dd June 14 2018
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.Dt CRONTAB 5
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.Os
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.Sh NAME
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|
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@ -31,117 +33,241 @@ A
|
|||
file contains instructions to the
|
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.Xr cron 8
|
||||
daemon of the general form:
|
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.Dq 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
|
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.Xr su 1
|
||||
as part of a cron command.
|
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.Dq at these times on these dates run this command .
|
||||
There may be a system
|
||||
.Nm
|
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and each user may have their own
|
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.Nm .
|
||||
Commands in any given
|
||||
.Nm
|
||||
will be
|
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executed either as the user who owns the
|
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.Nm
|
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or, in the case of the system
|
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.Nm crontab ,
|
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as the user specified on the command line.
|
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.Pp
|
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Blank lines and leading spaces and tabs are ignored.
|
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Lines whose first non-space character is a pound-sign
|
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.Pq Sq #
|
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While a
|
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.Nm
|
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is a text file, it is not intended to be directly edited.
|
||||
Creation, modification, and removal of a
|
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.Nm
|
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should be done using
|
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.Xr crontab 1 .
|
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.Pp
|
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Blank lines, leading spaces, and tabs are ignored.
|
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Lines whose first non-space character is a pound sign
|
||||
.Pq Ql #
|
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are comments, and are ignored.
|
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Note that comments are not allowed on the same line as cron commands, since
|
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Note that comments are not allowed on the same line as
|
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.Xr cron 8
|
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commands, since
|
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they will be taken to be part of the command.
|
||||
Similarly, comments are not
|
||||
allowed on the same line as environment variable settings.
|
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.Pp
|
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An active line in a crontab will be either an environment setting
|
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or a cron command.
|
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An environment setting is of the form,
|
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.Bd -literal
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name = value
|
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.Ed
|
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where the spaces around the equal-sign
|
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.Pq Sq =
|
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An active line in a
|
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.Nm
|
||||
is either an environment variable setting or a
|
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.Xr cron 8
|
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command.
|
||||
.Pp
|
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Environment variable settings create the environment
|
||||
any command in the
|
||||
.Nm
|
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is run in.
|
||||
An environment variable setting is of the form:
|
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.Pp
|
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.Dl name = value
|
||||
.Pp
|
||||
The spaces around the equal sign
|
||||
.Pq Ql =
|
||||
are optional, and any subsequent non-leading spaces in
|
||||
.Ar value
|
||||
will be part of the value assigned to
|
||||
.Ar name .
|
||||
The
|
||||
.Ar value
|
||||
string may be placed in quotes (single or double, but matching) to
|
||||
preserve leading or trailing blanks.
|
||||
string may be placed in quotes
|
||||
.Pq single or double , but matching
|
||||
to preserve leading or trailing blanks.
|
||||
.Pp
|
||||
Lines in the system
|
||||
.Nm
|
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have six fixed fields plus a command, in the form:
|
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.Bd -ragged -offset indent
|
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.Ar minute
|
||||
.Ar hour
|
||||
.Ar day-of-month
|
||||
.Ar month
|
||||
.Ar day-of-week
|
||||
.Ar user
|
||||
.Ar command
|
||||
.Ed
|
||||
.Pp
|
||||
While lines in a user
|
||||
.Nm
|
||||
have five fixed fields plus a command, in the form:
|
||||
.Bd -ragged -offset indent
|
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.Ar minute
|
||||
.Ar hour
|
||||
.Ar day-of-month
|
||||
.Ar month
|
||||
.Ar day-of-week
|
||||
.Ar command
|
||||
.Ed
|
||||
.Pp
|
||||
Fields are separated by blanks or tabs.
|
||||
The command may be one or more fields long.
|
||||
The allowed values for the fields are:
|
||||
.Bl -column "day-of-month" "allowed values" -offset indent
|
||||
.It Sy field Ta Sy allowed values
|
||||
.It Ar minute Ta * or 0\(en59
|
||||
.It Ar hour Ta * or 0\(en23
|
||||
.It Ar day-of-month Ta * or 1\(en31
|
||||
.It Ar month Ta * or 1\(en12 or a name (see below)
|
||||
.It Ar day-of-week Ta * or 0\(en7 or a name (0 or 7 is Sunday)
|
||||
.It Ar user Ta a valid username
|
||||
.It Ar command Ta text
|
||||
.El
|
||||
.Pp
|
||||
Lists are allowed.
|
||||
A list is a set of numbers (or ranges) separated by commas.
|
||||
For example,
|
||||
.Dq 1,2,5,9
|
||||
or
|
||||
.Dq 0\(en4,8\(en12 .
|
||||
.Pp
|
||||
Ranges of numbers are allowed.
|
||||
Ranges are two numbers separated with a hyphen.
|
||||
The specified range is inclusive.
|
||||
For example,
|
||||
8\(en11 for an
|
||||
.Ar hour
|
||||
entry specifies execution at hours 8, 9, 10 and 11.
|
||||
.Pp
|
||||
Step values can be used in conjunction with ranges.
|
||||
Following a range with
|
||||
.No / Ns Ar number
|
||||
specifies skips of
|
||||
.Ar number
|
||||
through the range.
|
||||
For example,
|
||||
.Dq 0\(en23/2
|
||||
can be used in the
|
||||
.Ar hour
|
||||
field to specify command execution every other hour.
|
||||
Steps are also permitted after an asterisk, so to say
|
||||
.Dq every two hours ,
|
||||
just use
|
||||
.Dq */2 .
|
||||
.Pp
|
||||
An asterisk
|
||||
.Pq Ql *
|
||||
is short form for a range of all allowed values.
|
||||
.Pp
|
||||
Names can be used in the
|
||||
.Ar month
|
||||
and
|
||||
.Ar 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
|
||||
.Ar name
|
||||
string may also be placed in quotes (single or double, but matching)
|
||||
to preserve leading, trailing or inner blanks.
|
||||
.Pp
|
||||
Several environment variables are set up automatically by the
|
||||
.Xr cron 8
|
||||
daemon.
|
||||
.Ar command
|
||||
field (the rest of the line) is the command to be
|
||||
run.
|
||||
The entire command portion of the line, up to a newline or %
|
||||
character, will be executed by
|
||||
.Pa /bin/sh
|
||||
or by the shell
|
||||
specified in the
|
||||
.Ev SHELL
|
||||
is set to
|
||||
.Pa /bin/sh ,
|
||||
and
|
||||
.Ev LOGNAME
|
||||
and
|
||||
.Ev HOME
|
||||
are set from the
|
||||
.Pa /etc/passwd
|
||||
line of the crontab's owner.
|
||||
.Ev HOME
|
||||
and
|
||||
.Ev SHELL
|
||||
may be overridden by settings in the crontab;
|
||||
.Ev LOGNAME
|
||||
may not.
|
||||
variable of the
|
||||
.Nm crontab .
|
||||
Percent signs
|
||||
.Pq Ql %
|
||||
in the command, unless escaped with a backslash
|
||||
.Pq Ql \e ,
|
||||
will be changed into newline characters, and all data
|
||||
after the first
|
||||
.Ql %
|
||||
will be sent to the command as standard input.
|
||||
.Pp
|
||||
(Another note: the
|
||||
.Ev LOGNAME
|
||||
variable is sometimes called
|
||||
.Ev USER
|
||||
on BSD systems... on these systems,
|
||||
.Ev USER
|
||||
will be set also.)
|
||||
Commands may be modified as follows:
|
||||
.Bl -tag -width Ds
|
||||
.It Fl n Ar command
|
||||
No mail is sent after a successful run.
|
||||
The execution output will only be mailed if the command exits with a non-zero
|
||||
exit code.
|
||||
The
|
||||
.Fl n
|
||||
option is an attempt to cure potentially copious volumes of mail coming from
|
||||
.Xr cron 8 .
|
||||
.It Fl q Ar command
|
||||
Execution will not be logged.
|
||||
.El
|
||||
.Pp
|
||||
In addition to
|
||||
.Ev LOGNAME ,
|
||||
.Ev HOME ,
|
||||
and
|
||||
.Ev SHELL ,
|
||||
Commands are executed by
|
||||
.Xr cron 8
|
||||
will look at
|
||||
.Ev MAILTO
|
||||
if it has any reason to send mail as a result of running commands in
|
||||
.Dq this
|
||||
crontab.
|
||||
If
|
||||
.Ev MAILTO
|
||||
is defined (and non-empty), mail is sent to the user so named.
|
||||
If
|
||||
.Ev MAILTO
|
||||
is defined but empty
|
||||
.Pq Ev MAILTO Ns = Ns \&"" ,
|
||||
no mail will be sent.
|
||||
Otherwise mail is sent to the owner of the crontab.
|
||||
This option is useful if you decide on
|
||||
.Xr mail 1
|
||||
instead of
|
||||
.Xr sendmail 1
|
||||
as your mailer when you install cron --
|
||||
.Xr mail 1
|
||||
doesn't do aliasing, and UUCP usually doesn't read its mail.
|
||||
.Pp
|
||||
In order to provide finer control over when jobs execute, users
|
||||
can also set the environment variables
|
||||
.Ev CRON_TZ
|
||||
when the
|
||||
.Ar minute ,
|
||||
.Ar hour ,
|
||||
and
|
||||
.Ev CRON_WITHIN .
|
||||
.Ar month
|
||||
fields match the current time,
|
||||
.Em and
|
||||
when at least one of the two day fields
|
||||
.Po Ar day-of-month
|
||||
or
|
||||
.Ar day-of-week Pc ,
|
||||
match the current time.
|
||||
.Pp
|
||||
Note: The day of a command's execution can be specified by two
|
||||
fields \(em
|
||||
.Ar day-of-month
|
||||
and
|
||||
.Ar day-of-week .
|
||||
If both fields are restricted (i.e. aren't *),
|
||||
the command will be run when
|
||||
.Em either
|
||||
field matches the current time.
|
||||
For example,
|
||||
.Pp
|
||||
.Dl 30 4 1,15 * 5
|
||||
.Pp
|
||||
would cause a command to be run at 4:30 am on the 1st and 15th of each
|
||||
month, plus every Friday.
|
||||
.Pp
|
||||
Instead of the first five fields, one of eight special strings may appear:
|
||||
.Bl -column "@midnight" "meaning" -offset indent
|
||||
.It Sy string Ta Sy meaning
|
||||
.It @reboot Ta Run once, at startup.
|
||||
.It @yearly Ta Run every January 1 (0 0 1 1 *).
|
||||
.It @annually Ta The same as @yearly.
|
||||
.It @monthly Ta Run the first day of every month (0 0 1 * *).
|
||||
.It @weekly Ta Run every Sunday (0 0 * * 0).
|
||||
.It @daily Ta Run every midnight (0 0 * * *).
|
||||
.It @midnight Ta The same as @daily.
|
||||
.It @hourly Ta Run every hour, on the hour (0 * * * *).
|
||||
.El
|
||||
.Sh ENVIRONMENT
|
||||
.Bl -tag -width "CRON_WITHIN"
|
||||
.It Ev CRON_TZ
|
||||
The
|
||||
.Ev CRON_TZ
|
||||
variable can be set to an alternate time zone in order to affect
|
||||
when the job is run.
|
||||
Note that this only affects the scheduling of the job, not the time
|
||||
zone that the job perceives when it is run.
|
||||
variable can be set to an alternate time zone in order to affect when the job
|
||||
is run.
|
||||
Note that this only affects the scheduling of the job, not the time zone
|
||||
that the job perceives when it is run.
|
||||
If
|
||||
.Ev CRON_TZ
|
||||
is defined but empty
|
||||
.Pq Ev CRON_TZ Ns = Ns \&"" ,
|
||||
jobs are scheduled with respect to the local time zone.
|
||||
.Pp
|
||||
.It Ev CRON_WITHIN
|
||||
The
|
||||
.Ev CRON_WITHIN
|
||||
variable should indicate the number of seconds within a job's
|
||||
|
|
@ -151,154 +277,58 @@ On a heavily loaded system, or on a system that has just been
|
|||
jobs will sometimes start later than originally intended, and by
|
||||
skipping non-critical jobs because of delays, system load can be
|
||||
lightened.
|
||||
If
|
||||
If
|
||||
.Ev CRON_WITHIN
|
||||
is defined but empty
|
||||
.Pa Ev CRON_WITHIN Ns = Ns \&""
|
||||
.Pq Ev CRON_WITHIN Ns = Ns \&"" ,
|
||||
or set to some non-positive value (0, a negative number, or a
|
||||
non-numeric string), it is treated as if it was unset.
|
||||
.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
|
||||
.Xr cron 8
|
||||
when the minute, hour, and month of year fields match the current
|
||||
time,
|
||||
.Em and
|
||||
when at least one of the two day fields (day of month, or day of week)
|
||||
match the current time (see
|
||||
.Dq Note
|
||||
below).
|
||||
.Xr cron 8
|
||||
examines cron entries once every minute.
|
||||
The time and date fields are:
|
||||
.Bl -column -offset indent "day of month" "0-7 (0 or 7 is Sun, or use names)"
|
||||
.It Em field Ta Em allowed values
|
||||
.It minute Ta 0-59
|
||||
.It hour Ta 0-23
|
||||
.It day of month Ta 1-31
|
||||
.It month Ta 1-12 (or names, see below)
|
||||
.It day of week Ta 0-7 (0 or 7 is Sun, or use names)
|
||||
.It Ev HOME
|
||||
Set from the user's
|
||||
.Pa /etc/passwd
|
||||
entry.
|
||||
May be overridden by settings in the
|
||||
.Nm .
|
||||
.It Ev LOGNAME
|
||||
Set from the user's
|
||||
.Pa /etc/passwd
|
||||
entry.
|
||||
May not be overridden by settings in the
|
||||
.Nm .
|
||||
.It Ev MAILTO
|
||||
If
|
||||
.Ev MAILTO
|
||||
is defined and non-empty,
|
||||
mail is sent to the user so named.
|
||||
If
|
||||
.Ev MAILTO
|
||||
is defined but empty
|
||||
.Pq Ev MAILTO = Qq ,
|
||||
no mail will be sent.
|
||||
Otherwise mail is sent to the owner of the
|
||||
.Nm .
|
||||
This is useful for pseudo-users that lack an alias
|
||||
that would otherwise redirect the mail to a real person.
|
||||
.It Ev SHELL
|
||||
Set to
|
||||
.Pa /bin/sh .
|
||||
May be overridden by settings in the
|
||||
.Nm .
|
||||
.It Ev USER
|
||||
Set from the user's
|
||||
.Pa /etc/passwd
|
||||
entry.
|
||||
May not be overridden by settings in the
|
||||
.Nm .
|
||||
.El
|
||||
.Pp
|
||||
A field may be an asterisk
|
||||
.Pq Sq * ,
|
||||
which always stands for
|
||||
.Dq first\-last .
|
||||
.Pp
|
||||
Ranges of numbers are allowed.
|
||||
Ranges are two numbers separated with a hyphen.
|
||||
The specified range is inclusive.
|
||||
For example,
|
||||
.Dq 8-11
|
||||
for an
|
||||
.Dq hours
|
||||
entry specifies execution at hours 8, 9, 10, and 11.
|
||||
.Pp
|
||||
A field may begin with a question mark
|
||||
.Pq Sq \&? ,
|
||||
which indicates a single value randomly selected when the crontab
|
||||
file is read.
|
||||
If the field contains only a question mark, the value is randomly
|
||||
selected from the range of all possible values for the field.
|
||||
If the question mark precedes a range, the value is randomly selected
|
||||
from the range.
|
||||
For example,
|
||||
.Dq ? ?2-5 * * *
|
||||
specifies that a task will be performed daily between 2:00am and
|
||||
and 5:59am at a time randomly selected when the crontab file is
|
||||
first read.
|
||||
As just one example, this feature can be used to prevent a large
|
||||
number of hosts from contacting a server simultaneously and
|
||||
overloading it by staggering the time at which a download script
|
||||
is executed.
|
||||
.Pp
|
||||
Lists are allowed.
|
||||
A list is a set of numbers (or ranges) separated by commas.
|
||||
Examples:
|
||||
.Dq 1,2,5,9 ,
|
||||
.Dq 0-4,8-12 .
|
||||
.Pp
|
||||
Step values can be used in conjunction with ranges.
|
||||
Following a range with
|
||||
.Dq / Ns Aq Mt number
|
||||
specifies skips of the number's value through the range.
|
||||
For example,
|
||||
.Dq 0-23/2
|
||||
can be used in the hours field to specify command execution every
|
||||
other hour (the alternative in the V7 standard is
|
||||
.Dq 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
|
||||
.Dq every two hours ,
|
||||
just use
|
||||
.Dq */2 .
|
||||
.Pp
|
||||
Names can also be used for the
|
||||
.Dq month
|
||||
and
|
||||
.Dq 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
|
||||
If the
|
||||
.Nm
|
||||
file is the system crontab
|
||||
.Pa /etc/crontab ,
|
||||
then the next (
|
||||
.Dq sixth )
|
||||
field contains the username to run the command as.
|
||||
.Pp
|
||||
The
|
||||
.Dq sixth
|
||||
field (or the
|
||||
.Dq seventh
|
||||
one for
|
||||
.Pa /etc/crontab )
|
||||
(the rest of the line) specifies the command to be run.
|
||||
The entire command portion of the line, up to a newline or percent
|
||||
signs
|
||||
.Pq Sq % ,
|
||||
will be executed by
|
||||
.Xr sh 1
|
||||
or by the shell specified in the
|
||||
.Ev SHELL
|
||||
variable of the cronfile.
|
||||
Percent signs
|
||||
.Pq Sq %
|
||||
in the command, unless escaped with backslash
|
||||
.Pq Sq \e ,
|
||||
will be changed into newline characters, and all data after the
|
||||
first % will be sent to the command as standard input.
|
||||
.Pp
|
||||
.Em 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 (i.e., aren't *), the command will
|
||||
be run when
|
||||
.Em either
|
||||
field matches the current time.
|
||||
For example,
|
||||
.Dq 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.
|
||||
.Pp
|
||||
Instead of the first five fields, one of eight special strings may appear:
|
||||
.Bl -column -offset indent "@annually" "Run once a month, 0 0 1 * *."
|
||||
.It Sy string Ta Sy meaning
|
||||
.It @reboot Ta Run once, at startup.
|
||||
.It @yearly Ta Run once a year, Dq 0 0 1 1 * .
|
||||
.It @annually Ta (same as @yearly)
|
||||
.It @monthly Ta Run once a month, Dq 0 0 1 * * .
|
||||
.It @weekly Ta Run once a week, Dq 0 0 * * 0 .
|
||||
.It @daily Ta Run once a day, Dq 0 0 * * * .
|
||||
.It @midnight Ta (same as @daily)
|
||||
.It @hourly Ta Run once an hour, Dq 0 * * * * .
|
||||
.Sh FILES
|
||||
.Bl -tag -width "/var/cron/tabs/<user>XXX" -compact
|
||||
.It Pa /etc/crontab
|
||||
System crontab.
|
||||
.It Pa /var/cron/tabs/ Ns Aq Ar user
|
||||
User crontab.
|
||||
.El
|
||||
.Ss EXAMPLE CRON FILE
|
||||
.Sh EXAMPLES
|
||||
.Bd -literal
|
||||
# use /bin/sh to run commands, no matter what /etc/passwd says
|
||||
SHELL=/bin/sh
|
||||
|
|
@ -306,53 +336,52 @@ SHELL=/bin/sh
|
|||
MAILTO=paul
|
||||
#
|
||||
# run five minutes after midnight, every day
|
||||
5 0 * * * $HOME/bin/daily.job \*[Gt]\*[Gt] $HOME/tmp/out 2\*[Gt]\*[Am]1
|
||||
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?%
|
||||
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"
|
||||
? ?2-4 1,15 * * echo "random between 2am-4:59am on the 1st and 15th"
|
||||
.Ed
|
||||
.Sh SEE ALSO
|
||||
.Xr crontab 1 ,
|
||||
.Xr cron 8
|
||||
.Sh STANDARDS
|
||||
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.
|
||||
.Dq 1-3,7-9
|
||||
would be rejected by ATT or BSD cron -- they want to see
|
||||
.Dq 1-3
|
||||
or
|
||||
.Dq 7,8,9
|
||||
ONLY.
|
||||
.Pp
|
||||
Ranges can include
|
||||
.Dq steps ,
|
||||
so
|
||||
.Dq 1-9/2
|
||||
is the same as
|
||||
.Dq 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
|
||||
.Pa /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).
|
||||
.Pp
|
||||
The
|
||||
.Nm
|
||||
file format is compliant with the
|
||||
.St -p1003.1-2008
|
||||
specification.
|
||||
The behaviours described below are all extensions to that standard:
|
||||
.Bl -dash
|
||||
.It
|
||||
The
|
||||
.Ar day-of-week
|
||||
field may use 7 to represent Sunday.
|
||||
.It
|
||||
Ranges may include
|
||||
.Dq steps .
|
||||
.It
|
||||
Months or days of the week can be specified by name.
|
||||
.It
|
||||
Mailing after a successful run can be suppressed with
|
||||
.Fl n .
|
||||
.It
|
||||
Logging can be suppressed with
|
||||
.Fl q .
|
||||
.It
|
||||
Environment variables can be set in a crontab.
|
||||
.It
|
||||
Command output can be mailed to a person other than the crontab
|
||||
owner, or the feature can be turned off and no mail will be sent
|
||||
at all.
|
||||
.It
|
||||
All of the
|
||||
.Sq @
|
||||
commands that can appear in place of the first five fields are
|
||||
extensions.
|
||||
.Ql @
|
||||
commands that can appear in place of the first five fields.
|
||||
.El
|
||||
.Sh AUTHORS
|
||||
.An Paul Vixie Aq Mt paul@vix.com
|
||||
.Nm
|
||||
was written by
|
||||
.An Paul Vixie Aq Mt vixie@isc.org .
|
||||
|
|
|
|||
Loading…
Reference in New Issue