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.\" $Id: crontab.5,v 1.4 1997/02/22 16:04:52 peter Exp $
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.Pp
47 name = value
48.Pp
49where the spaces around the equal-sign (=) are optional, and any subsequent
50non-leading spaces in
51.Em value
52will be part of the value assigned to
53.Em name .
54The
55.Em value
56string may be placed in quotes (single or double, but matching) to preserve
57leading or trailing blanks.
58.Pp
59Several environment variables are set up
60automatically by the
61.Xr cron 8
62daemon.
63.Ev SHELL
64is set to
65.Pa /bin/sh ,
66and
67.Ev LOGNAME
68and
69.Ev HOME
70are set from the
71.Pa /etc/passwd
72line of the crontab's owner.
73.Ev HOME
74and
75.Ev SHELL
76may be overridden by settings in the crontab;
77.Ev LOGNAME
78may not.
79.Pp
80(Another note: the
81.Ev LOGNAME
82variable is sometimes called
83.Ev USER
84on BSD systems...
85on these systems,
86.Ev USER
87will be set also).
88.Pp
89In addition to
90.Ev LOGNAME ,
91.Ev HOME ,
92and
93.Ev SHELL ,
94.Xr cron 8
95will look at
96.Ev MAILTO
97if it has any reason to send mail as a result of running
98commands in ``this'' crontab. If
99.Ev MAILTO
100is defined (and non-empty), mail is
101sent to the user so named. If
102.Ev MAILTO
103is defined but empty (MAILTO=""), no
104mail will be sent. Otherwise mail is sent to the owner of the crontab. This
105option is useful if you decide on
106.Pa /bin/mail
107instead of
108.Pa /usr/lib/sendmail
109as
110your mailer when you install cron --
111.Pa /bin/mail
112doesn't do aliasing, and UUCP
113usually doesn't read its mail.
114.Pp
115The format of a cron command is very much the V7 standard, with a number of
116upward-compatible extensions. Each line has five time and date fields,
117followed by a user name if this is the system crontab file,
118followed by a command. Commands are executed by
119.Xr cron 8
120when the minute, hour, and month of year fields match the current time,
121.Em and
122when at least one of the two day fields (day of month, or day of week)
123match the current time (see ``Note'' below).
124.Xr cron 8
125examines cron entries once every minute.
126The time and date fields are:
127.Bd -literal -offset indent
128field allowed values
129----- --------------
130minute 0-59
131hour 0-23
132day of month 1-31
133month 1-12 (or names, see below)
134day of week 0-7 (0 or 7 is Sun, or use names)
135.Ed
136.Pp
137A field may be an asterisk (*), which always stands for ``first\-last''.
138.Pp
139Ranges of numbers are allowed. Ranges are two numbers separated
140with a hyphen. The specified range is inclusive. For example,
1418-11 for an ``hours'' entry specifies execution at hours 8, 9, 10
142and 11.
143.Pp
144Lists are allowed. A list is a set of numbers (or ranges)
145separated by commas. Examples: ``1,2,5,9'', ``0-4,8-12''.
146.Pp
147Step values can be used in conjunction with ranges. Following
148a range with ``/<number>'' specifies skips of the number's value
149through the range. For example, ``0-23/2'' can be used in the hours
150field to specify command execution every other hour (the alternative
151in the V7 standard is ``0,2,4,6,8,10,12,14,16,18,20,22''). Steps are
152also permitted after an asterisk, so if you want to say ``every two
153hours'', just use ``*/2''.
154.Pp
155Names can also be used for the ``month'' and ``day of week''
156fields. Use the first three letters of the particular
157day or month (case doesn't matter). Ranges or
158lists of names are not allowed.
159.Pp
160The ``sixth'' field (the rest of the line) specifies the command to be
161run.
162The entire command portion of the line, up to a newline or %
163character, will be executed by
164.Pa /bin/sh
165or by the shell
166specified in the
167.Ev SHELL
168variable of the cronfile.
169Percent-signs (%) in the command, unless escaped with backslash
170(\\), will be changed into newline characters, and all data
171after the first % will be sent to the command as standard
172input.
173.Pp
174Note: The day of a command's execution can be specified by two
175fields \(em day of month, and day of week. If both fields are
176restricted (ie, aren't *), the command will be run when
177.Em either
178field matches the current time. For example,
179.br
180``30 4 1,15 * 5''
181would cause a command to be run at 4:30 am on the 1st and 15th of each
182month, plus every Friday.
183.Sh EXAMPLE CRON FILE
184.Bd -literal
185
186# use /bin/sh to run commands, no matter what /etc/passwd says
187SHELL=/bin/sh
188# mail any output to `paul', no matter whose crontab this is
189MAILTO=paul
190#
191# run five minutes after midnight, every day
1925 0 * * * $HOME/bin/daily.job >> $HOME/tmp/out 2>&1
193# run at 2:15pm on the first of every month -- output mailed to paul
19415 14 1 * * $HOME/bin/monthly
195# run at 10 pm on weekdays, annoy Joe
1960 22 * * 1-5 mail -s "It's 10pm" joe%Joe,%%Where are your kids?%
19723 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday"
1985 4 * * sun echo "run at 5 after 4 every sunday"
199.Ed
200.Sh SEE ALSO
201.Xr cron 8 ,
202.Xr crontab 1
203.Sh EXTENSIONS
204When specifying day of week, both day 0 and day 7 will be considered Sunday.
205BSD and ATT seem to disagree about this.
206.Pp
207Lists and ranges are allowed to co-exist in the same field. "1-3,7-9" would
208be rejected by ATT or BSD cron -- they want to see "1-3" or "7,8,9" ONLY.
209.Pp
210Ranges can include "steps", so "1-9/2" is the same as "1,3,5,7,9".
211.Pp
212Names of months or days of the week can be specified by name.
213.Pp
214Environment variables can be set in the crontab. In BSD or ATT, the
215environment handed to child processes is basically the one from
216.Pa /etc/rc .
217.Pp
218Command output is mailed to the crontab owner (BSD can't do this), can be
219mailed to a person other than the crontab owner (SysV can't do this), or the
220feature can be turned off and no mail will be sent at all (SysV can't do this
221either).
222.Sh AUTHOR
223.An Paul Vixie Aq paul@vix.com
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.\" $Id: crontab.5,v 1.4 1997/02/22 16:04:52 peter Exp $
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.Pp
47 name = value
48.Pp
49where the spaces around the equal-sign (=) are optional, and any subsequent
50non-leading spaces in
51.Em value
52will be part of the value assigned to
53.Em name .
54The
55.Em value
56string may be placed in quotes (single or double, but matching) to preserve
57leading or trailing blanks.
58.Pp
59Several environment variables are set up
60automatically by the
61.Xr cron 8
62daemon.
63.Ev SHELL
64is set to
65.Pa /bin/sh ,
66and
67.Ev LOGNAME
68and
69.Ev HOME
70are set from the
71.Pa /etc/passwd
72line of the crontab's owner.
73.Ev HOME
74and
75.Ev SHELL
76may be overridden by settings in the crontab;
77.Ev LOGNAME
78may not.
79.Pp
80(Another note: the
81.Ev LOGNAME
82variable is sometimes called
83.Ev USER
84on BSD systems...
85on these systems,
86.Ev USER
87will be set also).
88.Pp
89In addition to
90.Ev LOGNAME ,
91.Ev HOME ,
92and
93.Ev SHELL ,
94.Xr cron 8
95will look at
96.Ev MAILTO
97if it has any reason to send mail as a result of running
98commands in ``this'' crontab. If
99.Ev MAILTO
100is defined (and non-empty), mail is
101sent to the user so named. If
102.Ev MAILTO
103is defined but empty (MAILTO=""), no
104mail will be sent. Otherwise mail is sent to the owner of the crontab. This
105option is useful if you decide on
106.Pa /bin/mail
107instead of
108.Pa /usr/lib/sendmail
109as
110your mailer when you install cron --
111.Pa /bin/mail
112doesn't do aliasing, and UUCP
113usually doesn't read its mail.
114.Pp
115The format of a cron command is very much the V7 standard, with a number of
116upward-compatible extensions. Each line has five time and date fields,
117followed by a user name if this is the system crontab file,
118followed by a command. Commands are executed by
119.Xr cron 8
120when the minute, hour, and month of year fields match the current time,
121.Em and
122when at least one of the two day fields (day of month, or day of week)
123match the current time (see ``Note'' below).
124.Xr cron 8
125examines cron entries once every minute.
126The time and date fields are:
127.Bd -literal -offset indent
128field allowed values
129----- --------------
130minute 0-59
131hour 0-23
132day of month 1-31
133month 1-12 (or names, see below)
134day of week 0-7 (0 or 7 is Sun, or use names)
135.Ed
136.Pp
137A field may be an asterisk (*), which always stands for ``first\-last''.
138.Pp
139Ranges of numbers are allowed. Ranges are two numbers separated
140with a hyphen. The specified range is inclusive. For example,
1418-11 for an ``hours'' entry specifies execution at hours 8, 9, 10
142and 11.
143.Pp
144Lists are allowed. A list is a set of numbers (or ranges)
145separated by commas. Examples: ``1,2,5,9'', ``0-4,8-12''.
146.Pp
147Step values can be used in conjunction with ranges. Following
148a range with ``/<number>'' specifies skips of the number's value
149through the range. For example, ``0-23/2'' can be used in the hours
150field to specify command execution every other hour (the alternative
151in the V7 standard is ``0,2,4,6,8,10,12,14,16,18,20,22''). Steps are
152also permitted after an asterisk, so if you want to say ``every two
153hours'', just use ``*/2''.
154.Pp
155Names can also be used for the ``month'' and ``day of week''
156fields. Use the first three letters of the particular
157day or month (case doesn't matter). Ranges or
158lists of names are not allowed.
159.Pp
160The ``sixth'' field (the rest of the line) specifies the command to be
161run.
162The entire command portion of the line, up to a newline or %
163character, will be executed by
164.Pa /bin/sh
165or by the shell
166specified in the
167.Ev SHELL
168variable of the cronfile.
169Percent-signs (%) in the command, unless escaped with backslash
170(\\), will be changed into newline characters, and all data
171after the first % will be sent to the command as standard
172input.
173.Pp
174Note: The day of a command's execution can be specified by two
175fields \(em day of month, and day of week. If both fields are
176restricted (ie, aren't *), the command will be run when
177.Em either
178field matches the current time. For example,
179.br
180``30 4 1,15 * 5''
181would cause a command to be run at 4:30 am on the 1st and 15th of each
182month, plus every Friday.
183.Sh EXAMPLE CRON FILE
184.Bd -literal
185
186# use /bin/sh to run commands, no matter what /etc/passwd says
187SHELL=/bin/sh
188# mail any output to `paul', no matter whose crontab this is
189MAILTO=paul
190#
191# run five minutes after midnight, every day
1925 0 * * * $HOME/bin/daily.job >> $HOME/tmp/out 2>&1
193# run at 2:15pm on the first of every month -- output mailed to paul
19415 14 1 * * $HOME/bin/monthly
195# run at 10 pm on weekdays, annoy Joe
1960 22 * * 1-5 mail -s "It's 10pm" joe%Joe,%%Where are your kids?%
19723 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday"
1985 4 * * sun echo "run at 5 after 4 every sunday"
199.Ed
200.Sh SEE ALSO
201.Xr cron 8 ,
202.Xr crontab 1
203.Sh EXTENSIONS
204When specifying day of week, both day 0 and day 7 will be considered Sunday.
205BSD and ATT seem to disagree about this.
206.Pp
207Lists and ranges are allowed to co-exist in the same field. "1-3,7-9" would
208be rejected by ATT or BSD cron -- they want to see "1-3" or "7,8,9" ONLY.
209.Pp
210Ranges can include "steps", so "1-9/2" is the same as "1,3,5,7,9".
211.Pp
212Names of months or days of the week can be specified by name.
213.Pp
214Environment variables can be set in the crontab. In BSD or ATT, the
215environment handed to child processes is basically the one from
216.Pa /etc/rc .
217.Pp
218Command output is mailed to the crontab owner (BSD can't do this), can be
219mailed to a person other than the crontab owner (SysV can't do this), or the
220feature can be turned off and no mail will be sent at all (SysV can't do this
221either).
222.Sh AUTHOR
223.An Paul Vixie Aq paul@vix.com